Question posted by Ban from Singapore:

Grade/Level: 3

Question solved by Model Method: In a school, 5 times as many pupils signed up for the frisbee club as for the skating club. after 60 pupils transferred from the frisbee club to the skating club, both classes have the same number of pupils.

a) how many pupils signed up for the skating club at first?

b) how many pupils signed up for both classes?

Answer:

Step 1: Draw 5 boxes to represent the number of pupils who sign up for frisbee club and 1 box to represent the number of pupils who sign up for skating club.

Step 2: Since the 2 clubs had the same number of pupils after the transfer of 60 pupils, we "shift" 2 boxes from frisbee club's model to skating club's model thereby making the 2 model equal length. We can also label the 2 boxes shifted as 60 pupils.

Step 3: To find the number of pupils who sign up for skating club at first, we just need to work out what the value of 1 box/unit is. To find the number of pupils who sign up for both clubs, we just need to work out what the value of 6 boxes/units is.

Thus,

2 units ---------- 60

1 unit ---------- 60 / 2 = 30

6 units ---------- 30 x 6 = 180

Therefore,

(a) 30 pupils sign up for skating club at first.

(b) 180 pupils sign up for both clubs.