The table shows how much Shannon saves daily. For each subsequent day, she saves $9 more than the previous day.
- How much will Shannon save on Day 8?
- On which day will Shannon save $46?
- How much savings will Shannon have in total by the day found in part (b)?
(a)
Pattern for the amount saved
Day 1: 1 x 9 + 10 = $19
Day 2: 2 x 9 + 10 = $28
Day 3: 3 x 9 + 10 = $37
Day 4: 4 x 9 + 10 = $46
Formula
Amount saved = Day Number x 9 + 10
Amount saved on Day 8
= 8 x 9 + 10
= $82
(b)
Number of days that Shannon takes to save $46
= (46 - 10) ÷ 9
= 36 ÷ 9
= 4
(c)
Total savings that Shannon saves by Day 4
= 19 + 28 + ... + 37 + 46
= (19 + 46) x (4 ÷ 2)
= 65 x 2
= $130
Answer(s): (a) $82; (b) 4; (c) $130