Q&A - PSLE Math
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: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 ) -
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,
Some P6 pupils may find fractions slightly more difficult to handle than whole numbers.
One method to solve this, without having too many fractions in the working, is “The Denominators are Your Friends Method”
The denominators here are 10 and 5.
10 x 5 = 50
Let Chris have 50u of chocolates at first.
(50u stands for 50 units, or 50 boxes for those used to the Model Method.)
![](\"http://i50.tinypic.com/359fksl.jpg\")
http://i50.tinypic.com/359fksl.jpg\">
21u → 105 chocolates (left)
1u → 5 chocolates
50u → 250 chocolates (at first)
Hope this helps.
Cheers
speedmaths.com
PS.
Parents who wish to find out more about this method may wish to look at the “PSLE Maths Workshop for Parents” thread in the Happenings forum.
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jarenchuatw:
Hi
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)
Hope this helps.
Best wishes![](\"http://farm9.staticflickr.com/8005/7207450038_e911da4ea0_z.jpg\")
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