Q&A - PSLE Math

[youngtay]

Mr Tianzhu


Thanks

[peggy]

Hi need for this P5 qtn.


Hansel and Gretel had 720 sweets. Hansel gave 1/7 of his sweets to Gretel . In return Gretel gave 1/6 of her sweets to hansel. In the end they had an equal numberbof sweets each. How many sweets did hansel have at first?

Thanks!

[Muffins]

Hi peggy!


Lemme try to help:

In the end, they had 720 ÷ 2 = 360

360 × 6 = 2160

2160 ÷ 5 = 432 (what Gretel had after Hansel gave her 1/7 of his sweets)

720 - 432 = 288

288 ÷ 6 = 48

48 × 7 = 336 → What Hansel had in the beginning

Hope that helped!

[rossypolly]

PLs help me with this question. Thks


The ratio of the number of Andy's sweets to the number of Randy's sweets was 4:1.After Andy bought another 13 sweets & Randy was given 7 more by his sister, the ratio of Andy's sweets to Randy's sweets became 3:1.

How many sweets did Andy have at first?

[peggy]

Hi muffins,


Many thanks for your reply. But my maths is quite poor- not really able to understand. Any models to show?? Pai seh ah…

[atutor2001]

rossypolly:

PLs help me with this question. Thks


The ratio of the number of Andy's sweets to the number of Randy's sweets was 4:1.After Andy bought another 13 sweets & Randy was given 7 more by his sister, the ratio of Andy's sweets to Randy's sweets became 3:1.

How many sweets did Andy have at first?

This one can use model to show :


[...][...][...]-----Andy Before
[...]------------------Randy Before
[...][..7..]-----------Randy After
[...][..7..][...][..7..][...][..7..]---Andy After (note it is 3 groups of [...][..7..])
[...][...][...][...][........13.......]---Andy After (by adding '13' to BEFORE)

By comparing the last 2 models with re-arrangements we get :

[...][...][...][..7..][..7..][..7..]
[...][...][...][...][......13.......]

So 7 + 7 + 7 = 1 unit + 13

1 unit = 8

At first Andy has 4 units = 4 x 8 = 32 sweets

The sequence in developing the models is important if we want to get models that are easy to compare.

In this case, the sequence is A (before) to R (before) to R (after) to A (after in 2 ways)

[youngtay]

Hi, Please Help


1) In a pastry shop, the number of cakes was twice the number of cream puffs.After 90 cakes and 42 cream puffs were sold, the ratio of the number of cakes left to the number of cream puffs left was 2:5. How many cakes and cream puffs were in the shop at first?(Ans given 306)

2)Malik and Anuar shared a sum of $60. After their father gave each of them $16 more, Anuar had 10/13 of the amount of money Malik had. What fraction of the sum of $60 did Malik receive at first?

TIA

[tianzhu]

youngtay:

1) In a pastry shop, the number of cakes was twice the number of cream puffs.After 90 cakes and 42 cream puffs were sold, the ratio of the number of cakes left to the number of cream puffs left was 2:5. How many cakes and cream puffs were in the shop at first?(Ans given 306)

Hi youngtay

Good Evening

Please check the numbers in your questions.

I think you’ll get an answer of 137.25 based on the information given in your question.

Best wishes

[ADoc]

Cheerfuldad:

Hi all,


Please help!

Q. Tank X and Y are each filled with some water. If water from Tank Y is poured into Tank X until the water in Tank X reaches the brim, there will be 8 litres of water left in Tank Y. If water from Tank X is poured into Tank Y until the water in Tank Y reaches the brim, there will be 26 litres of water left in Tank X. The ratio of the volume of Tank X to the volume of Tank Y is 5:3. How many more litres of water are needed to fill both tanks to their brim?

Hi there! You can also to refer to my earlier post (another thread) for the solution using model.

cheers!

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=6373&postdays=0&postorder=asc&start=3230

[tianzhu]

youngtay:

2)Malik and Anuar shared a sum of $60. After their father gave each of them $16 more, Anuar had 10/13 of the amount of money Malik had. What fraction of the sum of $60 did Malik receive at first?

Hi

You may solve it with MD. I'll give you the pointers.

Anuar ------10 units
Malik ------- 13 units

23 units ----- 60+16+16 -------92
1 unit ------4

At first
Malik ---------52 – 16 -------36
36/60 ----------3/5

Best wishes