Q&A - PSLE Math
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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? -
Spongy:
AfterPlease 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?
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 -
:lovesite: Thank you very much master
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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. -
megamage1000:
HiHi, 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.
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 -
megamage1000:
HiHi, 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.
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 -
Chris had some M&M’s chocolates. He gave 3/10 of them to Ben and 2/5 of the remainder to Ken. He had 105 left. How many M&M’s chocolates had chris at first?
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Chris had some M&M’s chocolates. He gave 3/10 of them to Ben and 2/5 of the remainder to Ken. He had 105 left. How many M&M’s chocolates had chris at first?
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rose michelle:
Chris had some M&M's chocolates. He gave 3/10 of them to Ben and 2/5 of the remainder to Ken. He had 105 left. How many M&M's chocolates had chris at first?
Ben --> 3/10, remaining --> 7/10
Ken --> 2/5 x 7/10 = 7/25, remaining --> 7/10 - 7/25 = 21/50
21 units --> 105
1 unit --> 105/21 = 5
50 units --> 50 x 5 = 250
Ans : 250 -
rose michelle:
Chris had some M&M's chocolates. He gave 3/10 of them to Ben and 2/5 of the remainder to Ken. He had 105 left. How many M&M's chocolates had chris at first?
Hi ,
You can use the Branching method:
Total
/. \\
Ben. Remainder
3/10. 7/10
Remainder
/. \\
Ken. Left
2/5. 3/5
3/5 = 105
3 units = 105
1 unit = 35
5 units = 175 = 7/10
7 units = 175
1 unit = 25
10 units = 250
Ans: 250
(sorry if you can't see well cos i can't align the numbers properly here )
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