Q&A - PSLE Math

[2DMommy]

Need help with these 2 questions :


1)Denise and Jenette went shopping with a total of $380. After buying some items each, the amount Denise has left is 4 times the amount she spent and the amount Jeanette has left is thrice the amount she spent. The two friends had a total of $296 left. How much did Denise have at first ?

2)Nelson had 40% less money than Kai Lin. Maria had 20% more than the amount Nelson had. Maria spent 50% of her money on clothes and found that the amount she had left was $300 less than Nelson's. How much did Kai Lin have ?

Thank you in advance

[tianzhu]

2DMommy:

Need help with these 2 questions :


1)Denise and Jenette went shopping with a total of $380. After buying some items each, the amount Denise has left is 4 times the amount she spent and the amount Jeanette has left is thrice the amount she spent. The two friends had a total of $296 left. How much did Denise have at first ?

2)Nelson had 40% less money than Kai Lin. Maria had 20% more than the amount Nelson had. Maria spent 50% of her money on clothes and found that the amount she had left was $300 less than Nelson's. How much did Kai Lin have ?

Thank you in advance

Hi

Due to time constraints, I’ll be providing some pointers instead of MD.

For Q1, there are two variables. Using simultaneous concepts, you may solve it pictorially, using units and parts or simply using letters of the alphabet. There are some examples if you refer to the earlier posts.

For Denise
Left ----- D
Spent ----- DDDD

For Jenette
Left ----- JJJ
Spent ----- J

DDDD + JJJ ------ 296
D + J ----- 84
D + (3*84) ------ 296

D ----- 44

Hence, Denise had (44*5) or 220 at first.

For Q2, you may choose to work with percentages or units.

Kai Lin ----- 100%
Nelson ----- 60%
Maria ----- 72%

Maris spent 36% (half or 50%)

60 – 36 ----- 24

24% ----- 300
4% ------ 50

100% ------ 50*25 ------ 1250 (Kai Lin)

Best wishes

[Winx5015]

Hi, a very Happy New Year to all members of Kiasu Parents. :celebrat


Following is a question on algebra.

Jane has 4c marbles. Ivan has 1/3 the marbles Jane has. Gerald has 1/4 the marbles Ivan has. how many marbles does gerald have in terms of c?

Thanks :thankyou:

[MathIzzzFun]

Winx5015:

Hi, a very Happy New Year to all members of Kiasu Parents. :celebrat


Following is a question on algebra.

Jane has 4c marbles. Ivan has 1/3 the marbles Jane has. Gerald has 1/4 the marbles Ivan has. how many marbles does gerald have in terms of c?

Thanks :thankyou:

Hi

Gerald --> 1/4 of Ivan --> 1/4 of (1/3 of Jane) --> 1/4 x 1/3 x 4c = 1/3 c

cheers.

[Winx5015]

Hi mathIzzzFun,


Thanks for your help :thankyou:

[jesschan]

Can someone help me with the pattern question no. 29 on Nanyang’s CA1 Paper 1?


And does anyone have the complete question to Q18 of paper 2? The total area of triangles A & B is missing in my copy.

Many thanks!

[MathIzzzFun]

jesschan:

Can someone help me with the pattern question no. 29 on Nanyang's CA1 Paper 1?


And does anyone have the complete question to Q18 of paper 2? The total area of triangles A & B is missing in my copy.

Many thanks!

Hi

question no. 29 on Nanyang's CA1 Paper 1- work out the products in the diagonals and you should be able to see the pattern

cheers.

[jesschan]

MathIzzzFun:

jesschan:

Can someone help me with the pattern question no. 29 on Nanyang's CA1 Paper 1?


And does anyone have the complete question to Q18 of paper 2? The total area of triangles A & B is missing in my copy.

Many thanks!

Hi

question no. 29 on Nanyang's CA1 Paper 1- work out the products in the diagonals and you should be able to see the pattern

cheers.

Got it! Thanks.

[2DMommy]

Please help me with these 2 questions :

1)At first , Shop X has 156 kg of rice flour and Shop Y has 72 kg of rice flour. After each shop sold the same quantity of rice flour, the amount of rice flour that Shop X has was 4 times that of Shop Y. How many kilograms of rice flour did Shop X sell ?

2)An equal number of male and female runners took part in the National Education Marathon last year. 960 male runners and 350 female runners quit running and did not complete the marathon. The number of male runners left was 1/6 the number of female runners. What was the total number of runners at the start of the marathon ?

Thank you.

[mrswongtuition]

2DMommy:

Please help me with these 2 questions :

1)At first , Shop X has 156 kg of rice flour and Shop Y has 72 kg of rice flour. After each shop sold the same quantity of rice flour, the amount of rice flour that Shop X has was 4 times that of Shop Y. How many kilograms of rice flour did Shop X sell ?

2)An equal number of male and female runners took part in the National Education Marathon last year. 960 male runners and 350 female runners quit running and did not complete the marathon. The number of male runners left was 1/6 the number of female runners. What was the total number of runners at the start of the marathon ?

Thank you.

Question 1:
Constant Difference (the difference between the amounts of flour at each shop did not change).

156 - 72 = 84
Shop X has 84kg of flour more than Shop Y.

Since the amount of flour shop X has is 4 times as much as Shop Y after they each sold an equal quantity of flour:
X [--][--][--][--]
Y [--]<-84kg-->

3 units --> 84kg
1 unit --> 84/3 = 28kg
Shop Y had 28kg of flour left.

Since Shop X and Shop Y sold the same amount of flour, we can find out how much flour shop Y sold to get the answer:
72 - 28 = 44kg
Shop X sold 44kg of flour.



Question 2:

Start off drawing 'equal number at first':

M [----------------------------------------]
F [----------------------------------------]

Then add in 960 males left (and males are left with 1 unit),
350 females left (and females are left with 6 units):
M [u][-----------960-------------------]
F [u][u][u][u][u][u][-------350------]

From the above model, we can see that 5 units is 960 minus 350:
5 units --> 960-350 = 410
1 unit --> 82
There were 82 males left.

82 + 960 = 1042
There were 1042 males at first.

Since there were equal numbers of males and females, we can simply multiply the number of males by 2 to get the answer:
1042 x 2 = 2084
There were 2084 participants at first.