Maths Questions :)

Primary School Maths Questions & Solutions :D

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PSLE Maths 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 ?

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.




[EDITED: Typing mistake leading to calculation mistake. It should be:

From the above model, we can see that 5 units is 960 minus 350:
5 units --> 960-350 = 610
1 unit --> 122
There were 122 males left.

122 + 960 = 1082
There were 1082 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:
1082 x 2 = 2164
There were 2164 participants at first.]
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 ?
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.

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