Posts by roel

roel · Help Me !

hi... i'm back.. ahaha... sorry, i was not able to check this for a long time... I've been busy with my feasibility study..

But then, let's keep it going.. haha..

here's for

DAY 8

1. The average speed of a train is 20kph faster than that of a car. In 20 hours, the train covers the same distance that the car covers in 30 hours. what is the average speed of the train?

2. A can finish a job in 6 hours. After working for an hour, J helped him and together they finished the job in 2 more hours. How many hours will it take Joseph to finish the job if he will work alone?

3. Anthropologists can approximate the height of a primate by the size of the humerus by using the equation H = 1.2L + 27.8, where L is the length of the humerus and H is the height of the primate. Dr. A, an anthropologist, measured the height of a primate to be 66 inches, what is the approximate length of the humerus of his primate?
(I'm really having a hard time dividing when there is a decimal. especially when there is a decimal in both the divisor and dividend.)

4. If 5 workers can complete 9 chairs in 4 days, how long will it take for 8 workers to complete 18 chairs.

(there are some problems here that i already solved. I just don't know the reason why when i tried to solve it again, i didn't arrive at any answer.. ahaha.. any tip?)

we'll just have 4items.. so we can start with the new set of problems tomorrow...

thanks again...

roel · Help Me !

Here's for
DAY 7

1. Increasing the original saline solution by 12% and then increaseing the new solution by 25% is equivalent to increasing the original saline solution by how many percent?

2. Dr. A wishes to have 15 gallons of an 80% formaldehyde solution. In her inventory, she has a pure fomaldehyde and some 50% formaldehyde solution. How many gallons of pure formaldehyde should she mix to obtain the desired solution?

3.the total travel time for a family to reach a campsite is 2 hours. THey drive for 81km and hike for 2 km. If they drive 50kph faster than they hinke, what is their average driving speed?

4. Ryan travels in his car from north E to east E at a rate of 30kph and returns along the same route at a rate of 50kph. what is his average speed for the whole trip?

5. working alone, it takes twice as long for a helper to do a welding job as it would take for an experienced welder. If it takes a total of 8 hours for the two welders to complete the job working togeteher, how long does it take the helper to finish alone?

In these set, I don't really have an idea on how i should start answering it.

roel · Help Me !

mathsyperson wrote:

For questions like 1, it's easy to check for yourself whether your answer is right - you just check to make sure the given facts aren't contradicted.
You think that Trixie is 10, Numerico is 20 and Frezel is 22.
Check 1:Numerico's age is twice trixie's age.
20 = 2 x 10, so that's true.
Check 2:Frezel is 2 years more than twice trixie's age.
22 = 2 x 10 + 2, so that's true.
Check 3:The sum of numerico and trixie's age 2 years ago is equal to the age of Frezel 4 years from now.
(20-2)+(10-2) = 18+8 = 26 = (22+4), so that's true.
All conditions are met, so your answer works.

For 2, you're perfectly right, but the way I'd do it is to find the total cost of the 12kg of coffee, and then divide that by 12 at the end. It's just slightly less work.

thanks.. now I know..

roel · Help Me !

NullRoot wrote:

roel wrote:
4. every choice has a corresponding point. A is worth 5 points, B is 4 points, C is 3 points, and D is 2 points. Michelle got a total of 100 points. If she had 3 more B's than A's, 5 C's more than twice the number of A's and 6 D's less than thrice the number of A's, find the number of C's she got.
A - 5
B - 4
C - 3
D - 2
Michelle's
A = ?
B = 3 + A
C = 5 + 2A
D = 3A - 6
Here's how I went about it.
The A, B, C, and D are misleading, Roel. They give you the values for these so they aren't actually variables. They're what I would call a placeholder.
This is what I interpret her score to be:
100 = wA + xB + yC + zD
From the word problem we know:
x = 3+w
y = 5+2w
z = 3w-6
Substituting, including for the values of A,B,C,D:
100 = w5 + (3+w)4 + (5+2w)3 + (3w-6)2
100 = 5w + 12 + 4w + 15 + 6w + 6w - 12
100 = 21w + 15
85 = 21w
4.0476 ≈ w
So I think there may have been an error in copying somewhere? I'd expect only whole numbers given the context of the problem.

Thanks.. I checked the questionnaire, and I copied it right. Anyway, I trust you more here. So, i think It is the questionnaire itself that has the problem.. It's ok.. thanks again..

roel · Help Me !

Identity wrote:

5.
Let x be the amount of 20% acid solution that must be added in litres.
0.3(3)+0.2(x) = 0.26(3+x)
0.9 + 0.2x = 0.78 + 0.26x
0.06x = 0.12
x = 2
So he ought to add 2 litres of 20% acid solution.
These problems are really nice, lots of fun to do

How did you get the (3+x) in 0.3(3)+0.2(x) = 0.26(3+x)?

thanks identity. you're right.. lots of fun.. lots of headache, too...

roel · Help Me !

hey... thanks for the replies..

here's for our

DAY 6

1. Numerico's age is twice trixie's age. frezel is 2 years more than twice trixie's age. if the sum of numerico and trixie's age 2 years ago si equal to the age of Frezel 4 years from now, find the present age of Numerico.
(I tried to answer this.. But again, i don't know if i'm right)

N = 2T
F = 2+2T
T = ?

(N-2)+(T-2) = F + 4

so,

2T - 2 + T - 2 = 2 + 2T + 4
3T - 4 = 6 + 2T
T = 10 (is this the present age of Trixie? or her age 2 years ago?)

So

N=2(10) = 20?

2. A coffee brand that sells for P120 per kilo is mixed with another grade that sells 180 per kilo. If the amounts of two grades of coffee are 4 and 8 kilograms respectively, what should be the final selling price to even up the capital?

120 4 (120 x 4) / 12 = 40
180 8 (180 x 8) / 12 = 120
12 160

Is it 160? (did i do the right thing?)

3. The two legs of a triangle are 14 cm and 28 cm. what could be the length of the third side?
(i really don't know this.. except if it is a right triangle.. can you please give me all the formulas of a triangle? thanks)

4. every choice has a corresponding point. A is worth 5 points, B is 4 points, C is 3 points, and D is 2 points. Michelle got a total of 100 points. If she had 3 more B's than A's, 5 C's more than twice the number of A's and 6 D's less than thrice the number of A's, find the number of C's she got.

A - 5
B - 4
C - 3
D - 2

Michelle's
A = ?
B = 3 + A
C = 5 + 2A
D = 3A - 6

so,
what's next? ahaha...

5. A chemist wants to mix a 3-liter solution that is 30% acid to a solution that is 20% acid. How much of the 20% acid solution must he use to obtain a 26 % acid solution?

thanks again mates.. I wish i can have your mind...

roel · Help Me !

Here's for

DAY 5

1. Sol was offered two different jobs. The first job offers a starting salary of 9000 with a monthly increase of 100, while the second job offers an initial salary of 8400 and a monthly increase of 110. After how many years will the jobs pay equally?
(I tried to answer this.. But I'm not sure if it's right.. I'm still having a hard time interpreting/converting words into math ________...)

x - number of months

9000 + 100 x = 8400 + 110 x
600 = 10x
60 = x
(number of months in which the jobs will pay equally)

60/12 = 5 - number of years...

not sure about that.. nice try... ahaha

2. An airplane flew 360 miles in 3 hours against a headwind. The airplane made the return trip in 2 hours with a tailwind of the same velocity as the headwind. what was the airspeed of the plane without wind?

3. On a game show, a contestant is given four digits to arrange in a proper order to win a car. What is the probability of winning if the contestant guesses the position of each digit?

(I think it's

)

4. The average of a set of numbers is 78. If 32 is included in the set, the new average becomes 76. How many numbers are there in the original set?

I tried to answer this also.. But I'm not sure if my answer is right..

The average of a set of numbers is 78.

If 32 is included in the set, the new average becomes 76.

so

76y+44=78y
44=2y
22=y

(Is this right?)

5. Joan asked Jona to pick a card from a deck of cards. Find the probability of getting a black card or a number 6.

thanks again...

roel · Help Me !

mathsyperson wrote:

To get
instead of
, write "\times" wherever you want the x to be.
1. Your expression is
If you see any common terms on the numerator and denominator, you can get rid of them. Doing this for a while reduces the expression to
But if you write 6² as (2x3)², then you can simplify it further to 3²x7.
Evaluating that directly shows that the expression is equal to 63.

Uhm, if it's ok, I'm still confused with this problem... Is there another way of solving this? sorry...

2. Putting something between two "|" signs means you should knock off the minus sign if there is one. For example, |5| = 5, |-3| = 3, |0| = 0, etc.
So, after doing that, the expression becomes

From there it's fairly easy to work out what the value is.

i see.. I got it.. So it's 60

3.
4. Here we want a formula that relates Age (A) to Number of cigarettes (C).
We're told that for every year he smokes two more cigarattes a day, so we know that A = C/2 + ?
We're also told that he smoked 4 a day when he was 18, so plugging that in gets 18 = 4/2+?.
From that, we can work out that ?=16.
So the formula is A=C/2+16.
We want to know when he died, so we use C=40, which gives A = 40/2+16 = 20+16=36.
5. For this one, it's easier to work backwards.
When he meets the third guard, he gives him half his plants and two more, ending up with just one left. So if we say that he had x plants upon meeting the third guard, then the guard would get x/2+2 plants and he would keep 1.
So, (x/2+2)+1 = x, and so x/2=3, and so x=6.
The same equation can be used to work out how many the thief had when he met the second guard, except that he kept 6 plants at the end.
(x/2+2)+6 = x --> x/2=8 --> x = 16.
Do that one more time to find out how many plants the thief originally stole.

So, it's 36.. right?

Thanks for that.. Sorry I was not able to go online yesterday.. Everything is now clear.. Except that I am a bit confused with number 1. Thanks again..

roel · Help Me !

about the math problems you gave me, I am working on it.. All i can do is to smile everytime i see those problems.. those are really hard for me.. ahaha

roel · Help Me !

this one's for

DAY 4

1.

(all x here means multiply. How do you make the multiplication sign?)

2.

(what does "|" mean?)

3.

4. Jorge started smoking 4 cigarettes a day when he was 18 years old. Each year thereafter, he increased his consumption by 2 cigarettes a day. When he died of lung cancer, he was smoking 2 packs a day (40 cigarettes). How old was he when he died?
(i already have an answer here, but it took me too much time to solve this problem. So if there is an easier way, ......)

5. A thief steals a number of rare plants from a nursery. On his way out, the thief meets 3 security guards, one after another. To each security guard, the thief is forced to give one-half of the plants that he still has, plus 2 more. finally, the thief leaves the nursery with 1 lone palm. How many rare plants were originally stolen?

thanks again mates...

roel · Help Me !

ahaha.. that's what I did a while ago... I only answered 5 correct answers I think.. ahaha. I need some break.. I will try n to solve those problems again tomorrow. Thanks again mates..

roel · Help Me !

http://www.math.ksu.edu/main/handbook/ProblemSets

wew... i hope i wont be seeing questions in the LAT similar with those..

roel · Help Me !

Identity wrote:

I edited my previous post explaining the steps
Also:
or if you prefer,
but this is basically where my first solution reached on its second line.
These types of problems pop up all over competition papers. There is an excellent website where you can download them.
http://www.math.ksu.edu/main/handbook/ProblemSets
You can find these types of problems normally in the first 10-20 questions of the AMC papers. Good thing is you get the fully-worked solutions too! Have fun

I think, ill go with the first one... thanks again...

roel · Help Me !

thanks identity.. i will post again some problems tomorrow. please don't get tired helping me. Meanwhile, i will have a practice with the problems in the site you posted.. thanks again..

roel · Help Me !

where can i find some problems that are almost similar with all these?

roel · Help Me !

Identity wrote:

DAY 3
4 I use reciprocation twice here. It can be very useful.

Thanks.. everything is clear to me.. Except no. 4..

How did you get this?

is there another way of solving this?

Thanks Identity..

roel · Help Me !

Here's for:

DAY 3

1. An empty pool being filled with water at a constant rate takes 8 hours to fill

of its capacity. How much more time will it take to finish filling the pool?

2. A union contract specifies a 6% salary increase plus a P450 bonus for each employee. For a certain employee, this is equivalent to an 8% salary increase. what was the employee's salary before the contract?

3. Simplify

4. If

, find the value of x.

That's all for now so we can finish the first material.. Anyway, how can I make exponents here? i tried to copy the exponents above but everytime i use the [math] code, it won't appear..

Thanks again. i hope you won't get tired helping me...

roel · Help Me !

mathsyperson wrote:

You have to retain the denominator in that case because you're finding the value of an expression.
When you have an equation, you can do whatever you want to it, as long as you do the same thing on both sides of the equals sign. So at that step I just multiplied everything by 12.
You could keep the denominator in if you wanted to, and that would give you
.
At that point you would have to multiply by 12 in order to get x on its own.
Edit: Gah, beaten to it. Ah well, we agree at least.

I see.. I got it.. It is an equation if we're looking for a certain value of say, X right? and it is an expression if we are solving for the entire fraction, say adding 3/4 + 1/2?

thanks a lot mathsyperson..

roel · Help Me !

NullRoot wrote:

Roel,
Absolutely right on the elevator one.
For this one:
1. The denominator of a certain fraction is 3 less than twice the numerator. If 5 is added to both the numerator and the denominator, the denominator becomes 1 more than the numerator. Find the original fraction..
Try writing out the statements in terms of equalities.
So:
The denominator of a certain fraction is 3 less than twice the numerator.
D = (2N)-3
If 5 is added to both the numerator and the denominator, the denominator becomes 1 more than the numerator.
D+5 = 1+(N+5)
The second one can be cleaned up. You don't need to add A+B+C in any specific order, so the parenthesis are unnecessary; I used them to better represent the sentence. So:
D+5 = 1+N+5
If you Subtract 5 from both sides, then it simplifies to: D = 1+N, as TheDude said. Because we know this, we can take the first equality and have only 1 variable in it. We do this by substitution:
1+N = 2N-3
Adding 3 to both sides:
4+N = 2N
Subtract 1N from both sides:
4 = N
Putting N back into D=(2N)-3, you work out that D does in fact equal 5, so your fraction is 4/5. Good job
As far as Mathsyperson's solution, he just did two steps at once. When he added it all up, it would have come out to:
If you multiply both sides by 12, then you will cancel out the divison and arrive at:
Good luck with your Law test. I have a friend who's studying Criminal Justice at the moment .

oh really?

Thanks a lot for helping me NullRoot. .

roel · Help Me !

mathsyperson wrote:

To answer 3. from day 1, you make the fractions' denominators all match and then get rid of them. You can do that because the denominators are all constant (there aren't any x's in them).
Also, for future reference, you don't have to put each fraction in separate tags. You can make the code inside the tags as big as you want. The only problem with that is that if you make an error then it becomes harder to find it.

thanks.. but I am just a bit confused with solving fractions here.
Why is that in case we add for example

we retain the denominator? I.e.,

right?

But in this problem, why is the denominator 12 not retained? Sorry, i no longer remember what my teacher taught me...

thanks for your help..

roel · Help Me !

TheDude wrote:

1. We'll call the denominator d and the numberator n. We know that the denominator is 3 less than twice the numerator, which mathematically means d = 2n-3. We are also told that if 5 is added to both the numerator and denominator then the denominator becomes 1 more than the numerator, but this is the same as just saying that the denominator is 1 more than the numerator, which means d = 1+n. Since we know the value of d from the second equation we can substitute its value into the first equation to get d = 2n-3 ==> 1+n = 2n-3. You can now solve for both n and d.

So, in this case, i can disregard the statement If 5 is added to both n and d.. right?
So, the answer here is

?

5. The average weight of 10 people is the sum of all their weights divided by 10. Since their average weight is 145 pounds, their total combined weight is 1450 pounds. When one person leaves that means that there are now 9 people with an average weight of 150 pounds, which means their total weight is 1350. Subtract the weights and you'll find that the person that left weighed 100 pounds.

If n here refers to the person who got off the elevator. then

1450-n=1350
n=100
right?

thanks a lot..

The rest, I tried to solve it here, with your answers as my guide. And I got it! thanks for your help...

roel · Help Me !

Thanks to those who answered..

here's for:

DAY 2

1. The denominator of a certain fraction is 3 less than twice the numerator. If 5 is added to both the numerator and the denominator, the denominator becomes 1 more than the numerator. Find the original fraction..

for numbers 2-3

A launches her first painting exhibit. One of her paintings was sold. That painting has a length of 15 inches shorter than thrice its width and a perimeter of 98 inches.

2. Find the length, in inches, of the painting.

3. If the man who bought the painting paid P 673,200.00 for the painting, how much did he pay for every square inch of the painting?

4. A's bookshelf includes books of P books, G books, and M books. If the ratio of P books to G books is 5:3 and P books to M books is 6:4, what is the ratio of the number of M books to the number of G books?

5. The average weight of ten people in an elevator is 145 pounds. If one person gets off the elevator, the average weight of the remaining people is 150 pounds. What is the weight, in pounds, of the person who gets off the elevator?

Thanks again for your help...

roel · Help Me !

mathsyperson wrote:

5. Let's say that the initial price was x.
Then it was increased by 25%, and so the price became 5x/4.
It then dropped by 50%, to 5x/8.
We're told that this price is 250, and so we know that 5x/8 = 250.
Solve this: 5x/8 = 250 --> 5x = 2000 --> x = 400.
Therefore the original price was P400.

where did you get the 5 in 5x/4? sorry.. again, i am not good in math..:(

roel · Help Me !

thanks... I will print all the posts here in this thread.. I already have a reviewer.. ... can i post again tomorrow?

roel · Help Me !

Hi.. I am preparing for my Law aptitude test. Could you please help me answer the questions in my reviewer? I already have my own answers but i do not know if i answered it right. It is just because I am not good in math.. This is more than 90 questions i think. If it's ok, can I post 5 problems a day? please... This is the first five. Just tell me if i can post more next time.. Thanks...

DAY 1

1. If r≠0 and r=r-², what is the value of r?

2. Find the sum: 23 + 24 + 25 + ..........+ 70 + 71 + 72

(thanks to mathsyperson for helping me make the fractions...)

4. In a certain class, 1/2 of the male students and 2/3 of the female students read harry potter books. If there are 3/4 as many girls as boys in the class, what fraction of the entire class reads Harry Potter books?

5. The price of an item is increased by 25%. When the item was not sold, it is decreased by 50% of the increased price. If the item now costs P250, what is its original price?

If it's possible, please answer it in the simplest way since it's hard for me to understand complex solutions.. Thanks again.. I hope you'll allow me to post more next time.. Thanks..

Math Is Fun Forum

#1 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-12-20 04:12:28

#2 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-12-07 13:44:39

#3 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-12-07 12:41:43

#4 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-12-07 12:37:16

#5 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-12-07 12:30:17

#6 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-12-04 14:51:09

#7 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-12-01 15:22:28

#8 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-12-01 14:29:30

#9 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-29 17:21:28

#10 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-29 17:17:02

#11 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-28 23:08:33

#12 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-28 21:26:17

#13 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-28 21:14:55

#14 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-28 21:10:49

#15 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-28 19:44:22

#16 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-28 19:42:51

#17 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-28 15:12:17

#18 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-28 14:04:12

#19 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-28 14:00:25

#20 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-28 04:03:40

#21 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-28 03:41:52

#22 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-27 17:26:00

#23 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-26 15:20:36

#24 Re: Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-26 15:01:37

#25 Help Me ! » Quantitative reasoning for my Law Aptitude test.. » 2007-11-26 12:23:51

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