Harry received $1 from his aunt in the 1st week of school and $3 in the 2nd week. Each week, he receives $2 more than the week before.
- How much money did he received in the 20th week?
- In which week did he receive $25?
(a)
Amount that Harry received on 1st Week = $1
Amount that Harry received on 2nd Week = $19
Formula:
Amount received each week = 1 + (Week number - 1) x $2
Amount received on Week 20
= 1 + (20 - 1) x 2
= 1 + 19 x 2
= 1 + 38
= $39
(b)
Week number that Harry received $25
= [(25 - 1) ÷ 2] + 1
= (24 ÷ 2) + 1
= 12 + 1
= 13
Answer(s): (a) $39; (b) 13