Q&A - PSLE Math

[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

[zombie]

Can someone teach me or help to solve these questions using the constant difference/unchanged total method ? Thanks a lot ! :oops:


1) \tThere were 165 more chickens than ducks on a farm. If 60% of the chickens and 20% of the ducks were sold, the number of chickens left will be twice the number of ducks left. How many chickens were sold?

2)\tThere were 40% of girls in the Science Club. After another 30 girls joined the
\tScience Club, the percentage of girls increased by 15%. How many pupils
\twere there in the club at the end ?

3)\tKelly had 40% as much money as Mandy. After Mandy spent $66 on a dress, the percentage of Kelly’s money increased to 60%. How much money did Kelly have?

4)\tAiling has 10% more money than Belle and Belie has 25% more money than Cally. If Ailing has $78 more than Cally, how much do the three of them hove?

5)\tAdam has 30% as many stickers than Ben and 25% more cards than Chris. If they have a total of 462 stickers, how many stickers does Chris have?

6)\tLucas drank 45% of a bottle of pepsi. If he drank another 1 35m1, he would have drank 75% of it. How much pepsi was there in the bottle at first?

7)\tMr Low had 40% more cows than sheep. After he sold 375 cows and bought
\t375 sheep, he had 80% lesser cows than sheep. How many sheep did he have in the end?

8)\tAnne, Ben and Chris shared the cost of their seafood dinner. Anne paid 40% the total amount and Ben paid 30% of what Anne and Chris paid. If Ben paid $36 less than Chris, how much did Anne pay?

[KoalaBear37]

I think for qn 6, the ans is 450ml.


Method:
75%-45%=30%
30%->135ml
100%->135/300 x 100
=450ml

To check:
Total amount of pepsi:450ml
45% of 450ml:202.5ml
75% of 450ml:337.5ml
Difference:30%
Difference in ml:135ml

Ans:450ml

[KoalaBear37]

I think for qn 6, the ans is 450ml.


Method:
75%-45%=30%
30%->135ml
100%->135/300 x 100
=450ml

To check:
Total amount of pepsi:450ml
45% of 450ml:202.5ml
75% of 450ml:337.5ml
Difference:30%
Difference in ml:135ml

Ans:450ml

[Robertpattinsonidle]

how to do this qsn? my answer is 16 but answer key says 15. is it right? http://i50.tinypic.com/21cz5eh.jpg\">

[Zhu99]

Robertpattinsonidle:

how to do this qsn? my answer is 16 but answer key says 15. is it right? http://i50.tinypic.com/21cz5eh.jpg\">

Monday to Friday ---> 3 x 5 = 15

Saturday to Sunday ---> 6 x 2 = 12

15 + 12 = 27

60/27 = 2 weeks remainder $6 ---> Start saving on Sat or Sun to get the least number of days --- 1 day

7 + 7 + 1 = 15

The least number of days is 15.

[jarenchuatw]

Thanks Tianzhu, you got the answer right again, and the methods used is clearly illustrated

[kay22]

Mark and Nani were heading for their school from their homes. Mark started walking at a speed of 30 m/mim. At 6.45 am, Mark passed Nani’s flat and Nani started walking to the school at a certain speed. At 7 a.m., Nani was 150m ahead of Mark.


a) Find the speed at which Nani was walking.
b) If Nani reached the school 8 min ahead of Mark, at what time did Mark reach the school?