The table shows how much Zoe saves daily. For each subsequent day, she saves $4 more than the previous day.
- How much will Zoe save on Day 5?
- On which day will Zoe save $70?
- 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 4 + 10 = $14
Day 2: 2 x 4 + 10 = $18
Day 3: 3 x 4 + 10 = $22
Day 4: 4 x 4 + 10 = $26
Formula
Amount saved = Day Number x 4 + 10
Amount saved on Day 5
= 5 x 4 + 10
= $30
(b)
Number of days that Zoe takes to save $70
= (70 - 10) ÷ 4
= 60 ÷ 4
= 15
(c)
Total savings that Zoe saves by Day 15
= 14 + 18 + ... + 66 + 70
= (14 + 70) x (15 ÷ 2)
= 84 x 7.5
= $630
Answer(s): (a) $30; (b) 15; (c) $630
