The table shows how much Lynn saves daily. For each subsequent day, she saves $4 more than the previous day.
- How much will Lynn save on Day 9?
- On which day will Lynn save $118?
- How much savings will Lynn 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 9
= 9 x 4 + 10
= $46
(b)
Number of days that Lynn takes to save $118
= (118 - 10) ÷ 4
= 108 ÷ 4
= 27
(c)
Total savings that Lynn saves by Day 27
= 14 + 18 + ... + 114 + 118
= (14 + 118) x (27 ÷ 2)
= 132 x 13.5
= $1782
Answer(s): (a) $46; (b) 27; (c) $1782
