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## Topic review (newest first)

bobbym
2012-12-31 14:05:09

Hi;

That is very good! I see you had a lot of good help.

demha
2012-12-30 20:28:06

Thank you very much guys! I got a 10 on my final review!!

bob bundy
2012-12-27 21:12:29

hi demha

Well done.  Both answers, 16 and 40, are correct!

Bob

demha
2012-12-27 20:56:41

Hi Bob:
With your equation, I did the math and gor x = 40, so it will take 40 pounds of no-blue-grass seeds. Am I correct?

demha
2012-12-27 20:52:51

5 = 60/(x - 4)
x - 4 = 60/5
x - 4 = 12 (add 4 to both sides)
x = 16

So the rate will be 16 kilometers an hour in still water.
Am I heading the right direction?

demha
2012-12-27 20:44:35

Hi Bob:
I redid it again:

Seed Weight      Blue Grass      Weight Other Seed
0%     x                     0.00              (x)(just x will go here I believe)
30%   80                   24              (56)
20%    x + 80            0.2(x+80)              (0.8)(x + 80)

scientia
2012-12-27 20:30:49

#### demha wrote:

Hi Scientine:
I was taught how to do it using d = rt but wasn't understanding it right.

Now for what you shows me, am I supposed to substitute C for the current (which I got as 4) and then continue to solve for B?

Yes, you need to solve for b because the question is asking for the boat's speed in still water: in other words, what boat's speed would be if there were no current at all. The question isn't asking for the speed of the current (so your answer was not correct).

Bob bundy has created two tables for you for these two questions. Have a look. I think you might understand the questions better from the tables.

bob bundy
2012-12-27 19:52:16

hi demha

Seed Weight      Blue Grass      Weight Other Seed
0%     x                     0.00              (x)(just x will go here I believe)
30%   80                   24              (0.30)(56)X  just 56 here
20%    x + 80            16X(i)              (0.20)(x + 64)X(ii)

(i)The total amount in this row is x + 80.  20% of it should go here so put 0.2(x+80)

(i)And a similar expression here but this time for 80% of (x+80)

Now you are ready to solve the puzzle.

You can do the blue grass equation:  0 + 24 = 0.2(x+80)

or the other seed equation x + 56 = 0.8(x+80)

These should both give the same answer for x.

Check it works with the original problem.

Q4 and Q5.  I have put the details for both of these into a table as well.  (See below)

These three formulas are equivalent:

The answer will be in metres per minute.

Bob

demha
2012-12-27 19:01:09

Hi Scientine:
I was taught how to do it using d = rt but wasn't understanding it right.

Now for what you shows me, am I supposed to substitute C for the current (which I got as 4) and then continue to solve for B?

scientia
2012-12-27 17:26:41

#### demha wrote:

Hi Scientina:
I'm not too sure how t continue. Could you please help me a little on that?

What are you not too sure of? The two problems are similar, and I did almost all of question 4 for you. Just apply the concept speed = distance / time.

demha
2012-12-27 16:34:44

Seed Weight      Blue Grass      Weight Other Seed
0%     x                     0.00              (x)(just x will go here I believe)
30%   80                   24              (0.30)(56)
20%    x + 80            16              (0.20)(x + 64)

So is this right then?

bob bundy
2012-12-27 04:58:56

hi demha

Not quite.

Seed Weight      Blue Grass      Weight Other Seed
0%     x                     0.00              (0.00)(x)X(i)
30%   80                   0.30X(ii)              (0.30)(80)X(iii)
20%    x + 80            0.20X(iv)              (0.20)(x + 80)X(v)

(i)  This is the weight of the other seed.  If x lb is added and all is other seed what should go here?

(ii)  Work out 30% of 80 and write the answer here.

(iii)  Work out 70% of 80 and write the answer here.

(iv)  (x + 80) is correct for the first number in this row.  Write an expression for 20% of (x + 80) here.

(v)  And an expression for 80% of (x + 80) here.

Bob

demha
2012-12-27 03:47:15

Hi Bob:
Yes that's the one! I found that mistake soon after too. I remember adding that 12 there, I wonder how an x replaced it? o_O

As for the second chart, this is what I did:
Seed Weight      Blue Grass      Weight Other Seed
0%     x                     0.00              (0.00)(x)
30%   80                   0.30              (0.30)(80)
20%    x + 80            0.20              (0.20)(x + 80)

bob bundy
2012-12-27 02:49:59

hi

I was also wondering, did I do that chart correctly?

Do you mean this one:

A.
Amount of milk    Percentage(%)    Amount of buttermilk
1%     x                     (0.01)                    (0.01)x
4%     12                   (0.04)                    (0.04)12
2%     x + 12                   (0.02)                    (0.02)(x + 12)

There's a little error which I have corrected in red.

What I did is say that the first and second row figures for buttermilk must add up to the last row.

multiply by 100 to remove the decimals

Now how would I create tat chart?

In a word problem, I was taught to find out what I must calculate and call that x.

Then summarise all those words in a table with just the essential details.

There is the start mix, the added seeds and the final mix so the table will need three rows after the headings.

And there are three seed types to consider, mix, bluegrass alone, other seeds alone, so that makes three columns.

Rather than putting in % I converted everything into weights in lb.  That keeps it simple.

Row one plus row two must make row three.

I didn't bother with the final entry as it isn't needed to get x.  But you might like to try to complete it for the practice.  You can solve for x using column three as well.  try it.
Bob

bobbym
2012-12-27 02:09:19

hi demha;

Yes, I am getting 40 meters per minute for the windspeed.

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