Pei Chun Public Sch 2007 PSLE Math Prelim Q37

Mrs Durai wants to buy bookmarks for 3 classes of pupils. There are 35 pupils in each class. For every 4 bookmarks she buys, she gets another one free.
a) How many bookmarks does she need if each pupil gets 1 bookmark?
b) 4 bookmarks cost $2. What is the least amount she needs to pay?

Solution

a) 3 classes x 35 = 105

Answer: She needs 105 bookmarks.

b)
4 bookmarks + 1 free ----- $2
5 bookmarks (total) ----- $2

105 bookmarks divided by 5 ----- 21 (groups of 5 bookmarks)

21 groups of 5 bookmarks ----- 21 x $2 = $42

Answer: She has to pay $42.