Min was saving money to buy pens. She saved $8 every 4 days. After saving for 16 days, she went to buy pens that were on sale.
- What was the most number of pens she could buy?
- Min wanted to buy 21 pens. How much more did she need to save?
(a)
Number of sets of 4 days
= 16 ÷ 4
= 4
Amount that Min saved in 16 days
= 4 x 8
= $32
Maximum number of sets of 6 pens that Min could buy
= 32 ÷ 11
= 2 r $10
Remaining amount left after buying sets of 6 pens = $10
Maximum number of sets of 3 pens that Min could buy with $10
= 10 ÷ 6
= 1 r $4
Remaining amount left after buying sets of 3 pens = $4
Maximum number of pens that Min could buy with $4
= 4 ÷ 4
= 1
Most number of pens that Min could buy
= 2 x 6 + 1 x 3 + 1
= 12 + 3 + 1
= 16
(b)
Number of sets of 6 pens that Min could buy
= 21 ÷ 6
= 3 r 3
Number of sets of 3 pens that Min could buy
= 3 ÷ 3
= 1 r 0
Amount that Min needed to buy 21 pens
= 3 x 11 + 1 x 6
= 33 + 6
= $39
Amount that Min needed to save more
= 39 - 32
= $7
Answer(s): (a) 16; (b) $7
