Q&A - PSLE Math

[linden2000]

pixiedust:

Hi Tianzhu, MathIzzzfun,

I would also like to express my sincere THANKS to both of you for helping out with the numerous Maths questions, many which are from the school mock papers. My ds also did well for Maths this PSLE exam. I am very very grateful for your help ![/b]

Hi Tianzhu, MathIzzzfun,

Would also like to thank both of you for tirelessly helping to solve questions here. My DS did well for Maths in his PSLE. Though I've never posted questions here, I have spent quite a few nights poring over your solutions. Many thanks once again.

[lee tong fong]

Can you please help to solve this problem sum, thanks in advance


Ann,lan and Kelvin went shopping together. They bought a total of $580 with them. Ann spent 20% of her money, lan spent $30 and kelvin spent twice as much as Ann. At the end, they had $370 left. How much money did lan and Kelvin have together at first?

[Maths Hub]

lee tong fong:

Can you please help to solve this problem sum, thanks in advance


Ann,lan and Kelvin went shopping together. They bought a total of $580 with them. Ann spent 20% of her money, lan spent $30 and kelvin spent twice as much as Ann. At the end, they had $370 left. How much money did lan and Kelvin have together at first?

Total Amount Spent -> $580 - $370 = $210
Total Amount Spent by Ann and Kelvin -> $210 - $30 = $180
Since Ann spent 20% of her money and Kelvin spent twice as much as Ann, The amount Kelvin spent will be 40% of Ann's original amount of money.
20% + 40% = 60%
60% of Ann's money -> $180
100% of Ann's money -> $180 X 5/3 = $300
Amount of money Ian and Kevlin had together at first -> $580-$300=$280

[lee tong fong]

Great! Your working is clear and easy to understand and thanks for taking time to solve my questions.

[lee tong fong]

Can you please help to solve another 2 more problem sum, thanks in advance


1)In July, Pauline spent 20% of a sum of money on tuition, 60% on food and saved the rest. In August, the sum of money was increased by 15%. She spent the same amount of money on tuition but increased her saving by 30%. She saved $390 in August.
a)How much money did she spend on tuition in July?
b)How much did she spend on food in August?

2) Azman had 25% more marbles than chongfu. Chongfu has 60% more marbles than Bala. During a game, Azman and Bala lost some marbles to Chongfu in the ratio 3:1 . In the end, Azman and Bala had 780 and 480 marble left respectively. How many marbles did Azamn have at first?

[StaryNight]

lee tong fong:

Can you please help to solve another 2 more problem sum, thanks in advance


1)In July, Pauline spent 20% of a sum of money on tuition, 60% on food and saved the rest. In August, the sum of money was increased by 15%. She spent the same amount of money on tuition but increased her saving by 30%. She saved $390 in August.
a)How much money did she spend on tuition in July?
b)How much did she spend on food in August?

2) Azman had 25% more marbles than chongfu. Chongfu has 60% more marbles than Bala. During a game, Azman and Bala lost some marbles to Chongfu in the ratio 3:1 . In the end, Azman and Bala had 780 and 480 marble left respectively. How many marbles did Azamn have at first?

Hi lee tong fong,
this is the solution for the first question:
130/100 x 20 = 26 (% of money saved in August)
26%--> $390
1%--> $390/26 = $15
20%--> $15x20=300 (ans for part a)

(b)
100%--> 15x100=1500 (total sum of money in july)
1500-300-390=810 (ans for part b)

Hope this helps!

[lee tong fong]

Sure, your answer is correct and thank for your help.


Can you try to answer question 2. Thanks

[dazzlego]

Hi lee tong fong,


A:C = 125:100 = 5:4 (the one after the word than is always 100%)
C:B = 160:100 = 8:5
So A:B:C = 10:5:8 and A:B = 2:1

Rephrasing the questions to:
At first, A had 2 units and B has 1 unit. A lost 3 parts and B lost 1 part of their cards to C.
2u - 3p = 780
1u - 1p = 480

2u - 2p = 480 x 2 = 960
1p = 960 - 780 = 180
1u = 180 + 480 = 660
A: 2u = 660 x 2 = 1320

Cheers :celebrate:

lee tong fong:

Can you please help to solve another 2 more problem sum, thanks in advance

2) Azman had 25% more marbles than chongfu. Chongfu has 60% more marbles than Bala. During a game, Azman and Bala lost some marbles to Chongfu in the ratio 3:1 . In the end, Azman and Bala had 780 and 480 marble left respectively. How many marbles did Azamn have at first?

[lee tong fong]

Thanks for your answer and is it possible to use model instead of simultaneous equation to work out the solution.Thanks


2u - 3p = 780
1u - 1p = 480

2u - 2p = 480 x 2 = 960
1p = 960 - 780 = 180
1u = 180 + 480 = 660
A: 2u = 660 x 2 = 1320

[dazzlego]

lee tong fong:

Thanks for your answer and is it possible to use model instead of simultaneous equation to work out the solution.Thanks


2u - 3p = 780
1u - 1p = 480

2u - 2p = 480 x 2 = 960
1p = 960 - 780 = 180
1u = 180 + 480 = 660
A: 2u = 660 x 2 = 1320

Yes, it is possible. However since P6 students have already learned how to solve simultaneous equations, it's better to use it. This approach is less time consumed too.

Model:
2u = 3p + 780
1u = 1p + 480

http://i48.tinypic.com/21n2m49.jpg\">

1p = 480 + 480 - 780 = 180