The table shows how much Zoe saves daily. For each subsequent day, she saves $7 more than the previous day.
- How much will Zoe save on Day 7?
- On which day will Zoe save $129?
- How much savings will Zoe 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 7
= 7 x 7 + 10
= $59
(b)
Number of days that Zoe takes to save $129
= (129 - 10) ÷ 7
= 119 ÷ 7
= 17
(c)
Total savings that Zoe saves by Day 17
= 17 + 24 + ... + 122 + 129
= (17 + 129) x (17 ÷ 2)
= 146 x 8.5
= $1241
Answer(s): (a) $59; (b) 17; (c) $1241
