2021 PSLE Discussions and Strategies (Children born in 2009)

[StrictFather]

Blissedsher\" post_id=\"2040114\" time=\"1633076051\" user_id=\"23814:

lefrancaisestcool\" post_id=\"2040110\" time=\"1633074536\" user_id=\"180808:

[quote=wch post_id=2040103 time=1633073465 user_id=6988]May I know the steps?

Part (a):
Given that they both have the same number of coins, and Ivan has 40 more 20 cent coins than Helen, this means that both Helen has 40 more 50 cent coins than Helen, also meaning that she has more money.
Helen has 40(50C-30C)=$12 more than Ivan

Part (b)
Since Helen had 40 more 50 cent coins than Ivan, therefore her coins are (40x2.7g)=108g heavier than Ivan's coins. Then, simply subtract 108g from 1134g, which equals to 1026g or 1.026kg

May I know why minus 30c[/quote]The difference between 50 cts n 20 cts.
Alternatively the solution is (40×50) +(64×20) - (104×20) cts = 1200 cts = $12

[Pinkfellow]

As long as the kid drew the model, it should NOT be that difficult to solve.

[JULICC17]

Learnt from this math paper that parents really have to send their children to enrichment centres as schools do not teach questions like these. How will parents respect teachers and schools anymore.

[MummyPanda]

https://www.facebook.com/wakeupSG/photos/a.1617838598381759/2071414319690849/

[douzi]

JULICC17\" post_id=\"2040133\" time=\"1633081730\" user_id=\"136323:

Learnt from this math paper that parents really have to send their children to enrichment centres as schools do not teach questions like these. How will parents respect teachers and schools anymore.

Some schools go that deep, not all.

[Buyaoba1999]

Dependent on schools i think. Have seen similar questions before but with other objects (eg apples n pears n mass, coins n value). In this case, just ignore the masses first. My child’s school has a whole worksheet on these questions. Not sure if he did it right, didnt ask. His friends found the math paper to be easier than previous years, in that the questions are relatively straightforward.

[mummyof3angels]

Pinkfellow\" post_id=\"2040092\" time=\"1633072706\" user_id=\"137321:

Helen and Ivan had the same number of coins. Helen had a number of 50-cent coins and 64 20-cent coins. These coins had a mass of 1.134 kg. Ivan had a number of 50-cent coins and 104 20-cent coins .

(a) Who has more money in coins and by how much?(2)

(b) given that each 50-cent coin is 2.7g more heavier than a 20-cent coin, what is the mass of Ivan’s coins in kilograms? (2)

Question and solution here --
https://www.instagram.com/p/CUey2z2vwLZ/

My daughter managed to get this right but took her a while to figure it out.

[AHsDad]

With due respect, don’t think it’s so extreme that enrichment centre is now a must. My kid is from neighbourhood school and she said she came across the Helen question before in papers, plus Teachers also guided them before


But if really there are schools where this type question has never been discussed, then it’s a problem.

[dood21]

Pinkfellow\" post_id=\"2040092\" time=\"1633072706\" user_id=\"137321:

Helen and Ivan had the same number of coins. Helen had a number of 50-cent coins and 64 20-cent coins. These coins had a mass of 1.134 kg. Ivan had a number of 50-cent coins and 104 20-cent coins .

(a) Who has more money in coins and by how much?(2)

(b) given that each 50-cent coin is 2.7g more heavier than a 20-cent coin, what is the mass of Ivan’s coins in kilograms? (2)

I attempted this question so here is my solution but im not sure if it is corrrect:
let number of 50 cent coins Helen has be x
total coins of Helen = x+64(20 cent coins)
let number of 50 cent coins Ivan has be y
Total number of coins Ivan has = y+ 104 (20 cent coins)

Since both have the same number of coins
x+64 = y+104
x = y +40
Helen has 40 50 cent coins more than Ivan
(40 x 50) - (40 x 20) = 1200 cents
= 12 dollars
The answer is 12 dollars


(B)
Helen: x no. of 50 cent coins + 64 20 cent coins = 1.134kg
Ivan (has 40 less 50 cent coins and 40 more 20 cent coins)
Since total no. of coins remain the same and 50 cents coins are 2.7g heavier,
40 X 2.7 = 108g
1.134kg - 0.108 = 1.026kg
The answer is 1.026kg

Do let me know whether my working is correct

[happydaddy]

Well, you are using algebra leh. No mark given leh.