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 P5 Maths qn
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By: whitety (offline)  Tuesday, May 31 2011 @ 09:45 PM CDT (Read 2394 times)  
whitety

Hi,
Need some help on 2 P5 maths qns :
1) The ratio of Jane's mass to Peter's mass was 7:10. When Jane's mass was increased by 12.3kg and Peter's mass was decreased by 7.5kg, they would have the same mass. Find Peter's original mass.
2) A bus left the interchange with some passengers. At the first bus-stop, 1/10 of the passengers alighted and 9 passengers boarded the bus. At the second bus-stop, 2/5 of the passengers alighted and 8 passengers boarded the bus. There were 35 passengers on board the bus before it stopped at the third bus-stop. How many passengers boarded the bus at the interchange ?

Thanks for the help!

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By: chiucc2006 (offline)  Wednesday, June 01 2011 @ 04:21 AM CDT  
chiucc2006

I am not sure if the answer is correct.

J: P
7:10

Jane would be 12.3kg + 7.5kg lighter than Peter.
3 units would be 19.8kg
1 unit would be 19.8kg divide by 3
Peter's original weight would be 66kg.

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By: chiucc2006 (offline)  Wednesday, June 01 2011 @ 04:39 AM CDT  
chiucc2006

Find multiples of 10
20,20,30,40,50

You have to do some guess and check

I did and found that 40 is the answer

1/10 of 40 is 4.
4 people alighted from the bus.
36 people are left.
9 people boarded the bus.
So 45 people are on the bus before the second bus-stop.
2/5 of 45 is 18.
18 people alighted form the bus.
27 people are left.
8 people boarded the bus.
So 35 people are on the bus before the third bus-stop.

40 people boarded the bus at the interchange.

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By: joannleesw (offline)  Wednesday, June 01 2011 @ 08:09 PM CDT  
joannleesw

For Q2, there is no guess work required but it can be worked backwards.

3/5 units + 8 = 35
1/5 unit = 9
5/5 units = 45

9/10 units + 9 = 45
1/10 unit = 4
10/10 units = 40

Therefore, 40 passangers boarded the bus at the interchange.

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By: whitety (offline)  Wednesday, June 01 2011 @ 11:21 PM CDT  
whitety

Thanks for the great help! Big Grin

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By: learnandshare (offline)  Friday, June 03 2011 @ 10:50 AM CDT  
learnandshare

This question can be solved using the bar diagam.

Imagine there are 10 units : draw a bar with 10 segments. Once 1/10 of the passenger has alighted, you are left with 9 units.

Let the 9 units be called 9U and equate it to x; 9U= x

At the second stop, draw a bar with 5 segments but each of this segment is not equal to 1U. Let each of the segment be represented as V.

5V = x+9 (9 is added due to 9 passengers boarded the bus at station 1)

Hence, 2/5 of the passengers has alighted, you would have, have left with 3V before the 8 passengers board the bus at station 2.

Once the 8 passengers joined in, we would have 3V + 8 = 35.

Hence, V =9

x = 5(9) -9
x=36

Since from the start we know, 9U = x, hence; U= 4

Initially we have 10U which equates to: 10 *4 = 40 passengers.

Just try drawing it with blocks, and you will have a better appreciation of the question.

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By: whitety (offline)  Sunday, June 05 2011 @ 10:25 PM CDT  
whitety

Thanks for the help! Will try and understand all the different methods.

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