The table shows how much Sarah saves daily. For each subsequent day, she saves $7 more than the previous day.
- How much will Sarah save on Day 8?
- On which day will Sarah save $136?
- How much savings will Sarah have in total by the day found in part (b)?
(a)
Pattern for the amount saved
Day 1: 1 x 7 + 10 = $17
Day 2: 2 x 7 + 10 = $24
Day 3: 3 x 7 + 10 = $31
Day 4: 4 x 7 + 10 = $38
Formula
Amount saved = Day Number x 7 + 10
Amount saved on Day 8
= 8 x 7 + 10
= $66
(b)
Number of days that Sarah takes to save $136
= (136 - 10) ÷ 7
= 126 ÷ 7
= 18
(c)
Total savings that Sarah saves by Day 18
= 17 + 24 + ... + 129 + 136
= (17 + 136) x (18 ÷ 2)
= 153 x 9
= $1377
Answer(s): (a) $66; (b) 18; (c) $1377
