
need help!!!
Q1. Divide 64 into two parts so that the difference bettween 2/3 of one part and 1/4 of the other is equal to 28. What is the value of the larger part?
i hv did a little bit on tis qn... but i m stuck or isit i m wrong... my working: let the larger no. be x. let the smalelr no. be 64/x. 2/3x  1/4(64/x) = 28 2/3x  64/4x = 28 8x/12  192/12x = 28 i m stuck here...
Q2. A boy walks a certain distance at 9km/h. He finds that if he increases his speed by 1/3, he would have saved 4/3 hrs. Find the distance he walks.
for tis qn, i dun reli undertsand or know how 2 solve it... yarr...
 MathsIsFun
 Administrator
Re: need help!!!
Q1.
Full credit for having a go at it! You are using a good method, but I think the confusion is at the beginning. "Divide 64 into two parts" could mean "x times y equals 64" (as you thought of it), or "x plus y equals 64" (as in "let's divide this cake")
It works out neatly if you think of it as "x plus y equals 64"
So we can write it down as:
x+y=64 and (2/3)x  (1/4)y = 28 (like you had it)
Let's solve: x+y=64 y = 64x So: (2/3)x  (1/4)(64x) = 28 then: (2/3+1/4)x  (1/4)64 = 28 (8/12+3/12)x  16 = 28 (11/12)x=44 x= 44*12/11 = 4*12 = 48
Check it for me
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  Leon M. Lederman
 MathsIsFun
 Administrator
Re: need help!!!
Q2. A boy walks a certain distance at 9km/h. He finds that if he increases his speed by 1/3, he would have saved 4/3 hrs. Find the distance he walks.
I agree, it is hard to get your head around it.
Let's rephrase a little: 9km/h times (1+1/3) saves 4/3h, or an extra 3km/h saves 4/3h, so his time "t" is reduced.
OK, I think I can work this ... it has TWO things we don't know, time AND distance.
Let's call time "t" (in hours), and distance "x" (in km)
x = 9t (he went at 9km/h) x = 9(1+1/3)(t4/3) (increasing speed by 1/3 reduces time by 4/3)
Put the two together:
9t = 9(1+1/3)(t4/3) 9t = 12(t4/3) 9t = 12t48/3 9t = 12t16 3t = 16 t = 16/3
Check this, too
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  Leon M. Lederman
Re: need help!!!
gee... for question 1, i had checked and u are right! thank you... so my confusion is on the divide 64 into 2parts... thx alot!! but for question 2, i have not check yet... sorry... i will try to find the time to check.... thx anyway...
Last edited by sskl (20050405 19:56:29)
Re: need help!!!
I have forgotten how to find the square root of numbers by hand (without the use of a calculator), can anyone help me? Thanks Dannyk
 MathsIsFun
 Administrator
Re: need help!!!
Example: Square Root of 2 (but works generally)
Guess: 1.5
2/1.5 = 1.333 Average the guess and the answer: (1.5+1.333)/2 = 1.417
Again: 2/1.417 = 1.411 Average the guess and the answer: (1.417+1.411)/2 = 1.414 DONE!
So, the more times you do this, the more accurate it becomes, but you can see that we have quickly arrived at three decimal places of accuracy. Stuff like this is called Successive Approximation.
Let's try another one. Square root of 10
Guess: 4 10/4=2.5 (4+2.5)/2 = 3.25 10/3.25=3.077 (3.25+3.077)/2 = 3.163 Test: 3.163*3.163 = 10.004 Amazing!
This can be useful if you are stuck without a calculator and need to find the diagonal of a square. I used it once for placing survey pegs in the ground when I was far from home.
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  Leon M. Lederman
Re: need help!!!
i dont know how to divide numbers without the use of calculators but am embarassed to ask infront of my class, for example 19.50 / 83. please help me.
Last edited by classhelp (20050414 20:44:51)
 MathsIsFun
 Administrator
Re: need help!!!
Oh, you need a calculator for that !
Just kidding
19.5 / 83 would probably need long division. DECIMAL long division !
Looking at it, it would probably be easier written as 195/830 (it is the same, because I multiplied top AND bottom by the same number  10)
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  Leon M. Lederman
 MathsIsFun
 Administrator
Re: need help!!!
So, we are asking how many 830s go into 195
It is going to be less than 1, so we need to put some extra decimal places:
830 ) 195.000
First step is to guess where to start. Largest multiple of 830 that isn't TOOO big. 2 x 830 = 1660, so 0.2 x 830 = 166 is a good starting point"
0.2 830 ) 195.000 166.000
Now we have see how much is left to go:
0.2 830 ) 195.000 166.000 29.000
So let's work on the 29: 3 x 830 = 2490:
0.23 830 ) 195.000 166.000 29.000 24.9 4.1
So let's work on the 4.1: 4 x 830 = 3320:
0.234 830 ) 195.000 166.000 29.000 24.9 4.10 3.32 0.78
Ohh, thats far enough !!
19.5 / 83 = 195/830 = 0.234
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  Leon M. Lederman
 insomnia
 Real Member
Re: need help!!!
Friends are angels who lift our feet when our own wings have trouble remembering how to fly
 MathsIsFun
 Administrator
Re: need help!!!
Did I get it right, insomnia?
I just type and type, and hope I get it right
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  Leon M. Lederman
 insomnia
 Real Member
Re: need help!!!
It's 0.235, rounded up. So, you were close
Friends are angels who lift our feet when our own wings have trouble remembering how to fly
 Zach
 Super Member

Re: need help!!!
Boy let me tell you what: I bet you didn't know it, but I'm a fiddle player too. And if you'd care to take a dare, I'll make a bet with you.
 insomnia
 Real Member
Re: need help!!!
Friends are angels who lift our feet when our own wings have trouble remembering how to fly
 MathsIsFun
 Administrator
Re: need help!!!
OK, good enough. So long as it wasn't the PM figuring the next Budget I'm safe.
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  Leon M. Lederman
 Zach
 Super Member

Re: need help!!!
Boy let me tell you what: I bet you didn't know it, but I'm a fiddle player too. And if you'd care to take a dare, I'll make a bet with you.
 insomnia
 Real Member
Re: need help!!!
Some of them do. only like 3 people. They are all like secretaries,etc. Noone important knows.
Friends are angels who lift our feet when our own wings have trouble remembering how to fly
 MathsIsFun
 Administrator
Re: need help!!!
So they come here when the calcs get too hard.
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  Leon M. Lederman
 Zach
 Super Member

Re: need help!!!
Boy let me tell you what: I bet you didn't know it, but I'm a fiddle player too. And if you'd care to take a dare, I'll make a bet with you.
 insomnia
 Real Member
Re: need help!!!
Yep. They use you. You think they are maths questions, but in fact you are deciding the budget for them. But, they can't read and get it wrong and screw up the country
Friends are angels who lift our feet when our own wings have trouble remembering how to fly
Re: need help!!!
budget people use this site!! wow!!! i am coming here all the time. i can talk tot hem about how this country is annoying, with its silly governments.
the prime minister here!! that is amazing! am a baffled that they come here... amazing!!!!!
 Mr T
 Super Member
Re: need help!!!
I come back stronger than a poweredup PacMan I bought a large popcorn @ the cinema the other day, it was pretty big...some might even say it was "large Fatboy Slim is a Legend
Re: need help!!!
thats not nice BOOHOO. plz be nice. Or ill be mean to you
Vote Stewie and Mr T and static helper
Re: need help!!!
i was E=tally=3 last time, i didnt log in
Vote Stewie and Mr T and static helper
 Mr T
 Super Member
Re: need help!!!
sorry, i didn't know. it is my job to be mean to guests so that they join to hurl abuse at me. xcessive maths nerd is an example of this
I come back stronger than a poweredup PacMan I bought a large popcorn @ the cinema the other day, it was pretty big...some might even say it was "large Fatboy Slim is a Legend
