The table shows how much Eva saves daily. For each subsequent day, she saves $5 more than the previous day.
- How much will Eva save on Day 6?
- On which day will Eva save $165?
- How much savings will Eva have in total by the day found in part (b)?
(a)
Pattern for the amount saved
Day 1: 1 x 5 + 10 = $15
Day 2: 2 x 5 + 10 = $20
Day 3: 3 x 5 + 10 = $25
Day 4: 4 x 5 + 10 = $30
Formula
Amount saved = Day Number x 5 + 10
Amount saved on Day 6
= 6 x 5 + 10
= $40
(b)
Number of days that Eva takes to save $165
= (165 - 10) ÷ 5
= 155 ÷ 5
= 31
(c)
Total savings that Eva saves by Day 31
= 15 + 20 + ... + 160 + 165
= (15 + 165) x (31 ÷ 2)
= 180 x 15.5
= $2790
Answer(s): (a) $40; (b) 31; (c) $2790