Q&A - PSLE Math

[2632parent]

Hi tianzhu how do you get 16u for the apples and 20u for the orange. Thank you.

[tianzhu]

2632parent:

Hi tianzhu how do you get 16u for the apples and 20u for the orange. Thank you.

Hi

Apples:Oranges ------- 4:5 ------ 16:20

25% ------ 1/4

A common multiple for 4 and 5 is 20.

Best wishes

[tianzhu]

jarenchuatw:

Got 2 questions here needing help to solve:


Q1 A shopkeeper had some track shoes. 3/7 of them were brand X, 1/4 of the remainder were Brand Y and the rest were Brand Z. The ratio of the number of pairs of Brand X sold to the number of Brand Y to the number of Brand Z sold was 1:2:4. He sold 1/5 of all the shoes and was paid &840. How many pairs of Brand Z had he at
first?

Q2 see image attached

Hi

For Q1, I think some information might be missing.The amount of money earned for each pair of shoes for different brands is required.

For Q2, please attach the image.

Best wishes

[2632parent]

Oh my goodness how silly of me, thank you I understand now. Well have another question on speed , please help.


1) Abdul, Bernard and Chi Hao were all standing in a straight line waiting for the race to start. Chi Hao was 300m ahead of Bernard and Bernard was 100m ahead of Abdul. At 9a.m, they started the race. Abdul overtook Bernard in 5mins.
In another 5 mins, Abdul overtook Chi Hao. If Bernard’s speed is 150m/mins, at what time did Bernard overtake Chi Hao?

Thank you very much

[jarenchuatw]

You right, Tianzhu. I forgot to put in the following info:


X:$8 per pair
Y: $6 perbpair
Z: $10 per pair

[jarenchuatw]

http://i50.tinypic.com/2ugyn3q.jpg\"> And for Q2, attaching the image here.

[tianzhu]

2632parent:

1) Abdul, Bernard and Chi Hao were all standing in a straight line waiting for the race to start. Chi Hao was 300m ahead of Bernard and Bernard was 100m ahead of Abdul. At 9a.m, they started the race. Abdul overtook Bernard in 5mins.
In another 5 mins, Abdul overtook Chi Hao. If Bernard's speed is 150m/mins, at what time did Bernard overtake Chi Hao?

Thank you very much

Hi

Good Morning.

For Speed questions, it helps to start with a simple diagram.

This question touches on motion in the same direction where the faster runner overtakes the slower one. An important point to note is at the point of overtaking, the distance covered by both runners will be the same.

Bernard was 100m ahead of Abdul with a speed of 150m/min
Abdul overtook Bernard in 5min.

In 5 min, Bernard covered 150*5 or 750m/min

Abdul ------- 100 + 750 ------ 850 m/min

Hence, Abdul’s speed ------- 850/5 ------ 170m/min

Chi Hao was 300m ahead of Bernard.This means Chi hao was 400 m ahead of Abdul.

In 10 min, Abdul covered 1700 m

In 10 min ,Chi Hao ran 1300 m

Chi Hao’s speed ------ 1300/10 ------- 130 m/min.

In 1 min, Bernard is 20 m faster than Chi Hao

In 15 min, Bernard is 300 m faster than Chi Hao.

Bernard overtook Chi Hao at 9.15 am

Best wishes

[2632parent]

Good morning tianzhu, thank you for the solution.

[tianzhu]

jarenchuatw:

You right, Tianzhu. I forgot to put in the following info:


X:$8 per pair
Y: $6 perbpair
Z: $10 per pair

Hi

First find the number of parts for the different brands of shoes at first.

Brand X ------ 3/7 ------ 12 parts

Brand Y ------ 4 parts (1/4 of 16 parts)

Brand Z ------- 12 parts.

Next, find the number of shoes sold per brand using “Number*Value”

Brand X ------ 1*8 ------ 8u

Brand Y ------ 2*6 ------ 12u

Brand Z -------4*10 ------- 40u

60u ------- 840

1u ------ 14

Number of shoes sold ------- 7*14 -------- 98

Total number of shoes@first ------ 98*5 ------- 490

Number of brand Z@first -------- 12/28*490 ------- 210

Best wishes

[tianzhu]

jarenchuatw:

http://i50.tinypic.com/2ugyn3q.jpg\"> And for Q2, attaching the image here.

Hi

Volume of water --------- 2000*60 ------- 120000

Tank A base area --------- 50*40 -------- 2000

Tank B base area --------- 70*40 -------- 2800

Height ( after pouring) -------- 120000/4800 ------- 25

Best wishes