Q&A - PSLE Math

[jarenchuatw]

Thanks, BB for the answer…u made it look so simple.

[jarenchuatw]

These 2 P6 practice questions had me pulling my hair out, trying to figure how to solve it....apprecaite all the help out there, so that I can explain to my boy :stupid:


Q1 Raymond had 20% fewer stamps than Johnny. Lingling had 60% of the number of stamps Raymond had. Raymond gave 48 stamps to Lingling and both of them had the same number of stamps. How many stamps must Johnny give to Lingling so that both would have the same number of stamps? (Answer: 54stamps)

Q2 XiaoMing and Mary each had a certain number of comics. Xiao Ming gave away 40% of his comics and another 15% of his remaining comics to Mary. Then Mary gave 2/3 of her comics to Sally. Xaioming found that he had thrice as many comics left as Mary. If Mary had 210 comics at first,
(a) how many comics did Xiao Ming have at first? (Answer: 500)
(b) how many comics did Sally receive from Mary? (Answer : 170)

[szepinge]

Raymond 80% = 4u x 5 = 20u

Johnny 100% = 5u x 5 = 25u

Ling ling 3u x 4 = 12u
Raymond 5u x 4 = 20u

Make Raymond the same number of units
Repeated identity

Raymond must give 4u to ling ling so that both have 16 units
4U = 48
1u = 12
Ling ling have 16u now after Raymond give her 4u

Johnny must give 4.5 units to lingling
So that both have 20.5 units after that.

4.5 x 12 = 54 stamps

[Michaelia0816]

Yay! My exam marks was back, 30 for paper 1 and almost got a* by a few marks! Scoring super well in paper 2!

[Spongy]

Please help! thanks in advance.


There was a total of 820 boys and girls in a school hall. After 3/4 of the boys had left the hall and another 75 girls had entered it, there is now an equal number of boys and girls in the hall. How many more boys than girls were there in the hall initially?

[php]

Spongy:

Please help! thanks in advance.


There was a total of 820 boys and girls in a school hall. After 3/4 of the boys had left the hall and another 75 girls had entered it, there is now an equal number of boys and girls in the hall. How many more boys than girls were there in the hall initially?

After
Boy - 1u, Girl - 1u

Before - 4u, Girl - 1u - 75

4u + 1u - 75 --> 820
5u --> 820 + 75 = 895
1u --> 179

Before
Boy --> 4u = 4 x 179 = 716
Girl --> 1u - 75 = 179 - 75 = 104

Ans : 716 - 104 = 612

[Spongy]

:lovesite: Thank you very much master

[megamage1000]

Hi, i have a hard time resolving this question, Hope you will help me!


In a photocopier shop, Copier A was turned on first, and it printed 240 pages.Then Copier B was turned on , and Copier A and Copier B continue printing together.For every 4 pages Copier A printed, Copier B printed 7 pages . Copier B printed 30 pages fewer than 2/7 of the total number of pages printed.

Find the total number of pages printed.

[Yu Xuan]

megamage1000:

Hi, i have a hard time resolving this question, Hope you will help me!


In a photocopier shop, Copier A was turned on first, and it printed 240 pages.Then Copier B was turned on , and Copier A and Copier B continue printing together.For every 4 pages Copier A printed, Copier B printed 7 pages . Copier B printed 30 pages fewer than 2/7 of the total number of pages printed.

Find the total number of pages printed.

Hi

A --> 5 units + 30
B --> 2 units - 30
Total --> 7 units

By removing the 240 printed earlier by A, both machine worked for the same amount of time and hence we can relate their output to their respective speed ratio;
4 parts --> 5 units + 30 -240 = 5 units - 210
7 parts --> 2 units - 30

28 parts --> 35units - 1470
28 parts --> 8units - 120
draw a model to represent the 28 parts, you will see that,
27 units --> 1470 - 120 = 1350
1 unit --> 50
7 units --> 50 x 7 = 350

Yuxuan

[tianzhu]

megamage1000:

Hi, i have a hard time resolving this question, Hope you will help me!


In a photocopier shop, Copier A was turned on first, and it printed 240 pages.Then Copier B was turned on , and Copier A and Copier B continue printing together.For every 4 pages Copier A printed, Copier B printed 7 pages . Copier B printed 30 pages fewer than 2/7 of the total number of pages printed.

Find the total number of pages printed.

Hi

A neat way is to use MD. Alternatively, you may also use “Units and Parts”.

Use equivalent ratios to avoid working with decimals.

For every 4 pages Copier A printed, Copier B printed 7 pages .

Copier A ----- 4 units ------ 8 units
Copier B ----- 7 units ------ 14 units

Total number of pages ------- 7 parts.

14 units + 30 ------- 2 parts

7 units + 15 ------ 1 part

49 units + 105 ------- 7 parts

49 units + 105 ------ 240 + 8 units + 14 units

27 units ------- 135
1 unit ------- 5

Total number of pages printed -------- (49*5) + 105 -------- 350.

Best wishes