Q&A - PSLE Math

[speedmaths.012624com]

parents222:

Hi, please help me with these 2 questions, is urgent, many thanks!


Nancy has 10-cent and 20-cent coins in the ratio of 5:6. When she spends eight 20-cent coins, the value of 20-cent coins is $0.20 less than that of the 10-cent coins. How many 10-cent coins does Nancy have?

Hi,

When she spends eight 20-cent coins (or $1.60), the value of 20-cent coins is $0.20 less than that of the 10-cent coins.

Before spending the $1.60 in 20-cents coins, the value of 20-cent coins is ($1.60 - $0.20 $1.40 more than that of the 10-cent coins.

Ratio of 10-cent and 20-cent coins is 5:6, or 10:12.

10 x 10-cent coins is $1.00.
12 x 20-cent coins is $2.40.
Difference is $1.40.

Answer: Nancy has ten 10-cent coins.

Hope this helps.

speedmaths.com


.

[speedmaths.012624com]

kuts:

Andy, George and Dim agreed to buy present together. Andy agreed to contribute 30% of the cost of the present. George agreed to contribute 2/5. The balance will be paid by Dim. However, when they went to the shop, the cost of the present increased by 25%. As a result, Andy paid $84.

a. What is the original price of the present
b. How much did Dim had to pay at the end?

Hi,

One possible method:

Let the original price of the present be 100u.
(100u is short for 100 units, or 100 boxes [for those used to drawing boxes using the Model Method])

Andy to contribute 30% of 100u or 30u.
George to contribute 2/5 of 100u or 40u.
Dim to contribute the remaining 30u.

Let the new cost of the present be 1.25 x 100u → 125u.
Andy now has to pay 1.25 x 30u → 37.5u.
37.5u → $84
1u → $84 / 37.5
Original price of the present is 100u → 100 x $84 / 37.5 → $224.

Can you work from here?

Cheers


speedmaths.com

.

[Essential]

Good morning Tianzhu , thanks for the detailed N eye- catching posting .

[tianzhu]

Essential:

Good morning Tianzhu , thanks for the detailed N eye- catching posting .

Hi

Good Morning.

You're welcome.

Best wishes

[kuts]

Thanks a lot for ur explanation.

[kuts]

Thank you green belt for ur wonderful explanation! Tks a lot

[tianzhu]

Michaelia0816:

You meant Unit and Part Method (UP), I tried to find the ways to solve using it, I also think UP is the best way, but sometime, I do forget how to use it!!!

Hi

Good Morning, girl.

Well, forgetting is a natural process.

Sometimes, adults forget too.

It’s comforting to know forgetting and tendency to make careless mistakes are some things all students in the world are capable of making.

The students who make fewer mistakes and lose fewer points than other fellow students will usually fare better.

Well, talking about UP, children at your age are ……..

Usually with their iPad

Usually like to be at the Playgrounds.

Usually PSLE is a Usual Part of a child’s life.

It’s not the only part; it’s the beginning of a long life journey.

Put in your best efforts, be the best you can be.

Pay attention to your teachers and listen to your Understanding Parents.

Learn UP, understand UP and apply UP and your marks will go UP. If you want to forget UP, please do it after PSLE.

Here’s another slide which I hope will help to reinforce your understanding of UP.As you can see, the concept is not too difficult to grasp. The steps are rather mechanical and not too tedious. Equalise the final parts and you’re on the way to your 5 points.

Enjoy your studies.

Best wishes

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[lousymum]

Help pls.


(1) Michael jogged while Karen walked from the same place but in opposite directions along a straight road. After 5h, they were 30 km apart. Michael’s average speed was 1.2 km/h faster than Karen’s average speed. What was Karen’s average walking speed?

(2) Ben and Macus received some moey from their mother. Marcus would have $64 more than Ben if Ben gave 2/5 of his share to Marcus. Marcus would have $144 more than Ben if Ben gave 2/3 of his share to Marcus. How much money did Ben receive from his mother?

Thanks.

[tianzhu]

lousymum:

Help pls.

(1) Michael jogged while Karen walked from the same place but in opposite directions along a straight road. After 5h, they were 30 km apart. Michael's average speed was 1.2 km/h faster than Karen's average speed. What was Karen's average walking speed?

Hi

There’s a few ways to solve it.

For questions on Speed, it’s useful to start with a simple diagram.

If Karen’s distance travelled in 5h is showed by 1 unit or 1 box, then Michael’s distance travelled in 5h would be 1 unit or 1 box + (5*1.2)

Hence we have 2 boxes or units + 6 ------- 30

This gives 1 unit/box ------- 12

Therefore, Karen’s speed -------- 12/5 ------- 2.4

Best wishes

[tianzhu]

lousymum:

(2) Ben and Macus received some moey from their mother. Marcus would have $64 more than Ben if Ben gave 2/5 of his share to Marcus. Marcus would have $144 more than Ben if Ben gave 2/3 of his share to Marcus. How much money did Ben receive from his mother?

Hi

There are two scenarios in this question.

Marcus would have $64 more than Ben if Ben gave 2/5 of his share to Marcus.

A common multiple of 3 and 5 is 15

Marcus -------9 units + 64
Ben -------- 9 units

Marcus would have $144 more than Ben if Ben gave 2/3 of his share to Marcus

Marcus -------5 units + 144
Ben -------- 5 units

The total amount of money in both scenarios stays the same.

18 units + 64 ------- 10 units + 144
8 units -------- 80
1 unit ------- 10

Ben ------- 15 units -------- 150

Best wishes