The table shows how much Shannon saves daily. For each subsequent day, she saves $8 more than the previous day.
- How much will Shannon save on Day 11?
- On which day will Shannon save $170?
- 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 8 + 10 = $18
Day 2: 2 x 8 + 10 = $26
Day 3: 3 x 8 + 10 = $34
Day 4: 4 x 8 + 10 = $42
Formula
Amount saved = Day Number x 8 + 10
Amount saved on Day 11
= 11 x 8 + 10
= $98
(b)
Number of days that Shannon takes to save $170
= (170 - 10) ÷ 8
= 160 ÷ 8
= 20
(c)
Total savings that Shannon saves by Day 20
= 18 + 26 + ... + 162 + 170
= (18 + 170) x (20 ÷ 2)
= 188 x 10
= $1880
Answer(s): (a) $98; (b) 20; (c) $1880
