Adam saves $3 in the 1st week and $5 in the 2nd week.
Each week, he saves $2 more than the week before.
- How much money does he save in the 6th week?
- In which week does he save $31?
(a)
Amount that Adam saves on Week 1: $3
Amount that Adam saves on Week 2: $5 = 3 + 2 = 3 + (2 x 1)
Amount that Adam saves on Week 3: $7 = 3 + 2 + 2 = 3 + (2 x 2)
Amount that Adam saves on a certain week = 3 +(2 x (Week number - 1))
Amount that Adam saves on Week 6
= 3 + 2 × (6 - 1)
= 3 + 2 × 5
= 3 + 10
= $13
(b)
3 + 2 x (Week number - 1) = 31
2 x (Week number - 3) = 31 - 3
2 x (Week number - 3) = 28
Week number - 1 = 28 ÷ 2
Week number - 1 = 14
Week number = 14 + 1
Week number = 15
Answer(s): (a) $13; (b) 15
