The table shows how much Ivory saves daily. For each subsequent day, she saves $12 more than the previous day.
- How much will Ivory save on Day 11?
- On which day will Ivory save $190?
- How much savings will Ivory have in total by the day found in part (b)?
(a)
Pattern for the amount saved
Day 1: 1 x 12 + 10 = $22
Day 2: 2 x 12 + 10 = $34
Day 3: 3 x 12 + 10 = $46
Day 4: 4 x 12 + 10 = $58
Formula
Amount saved = Day Number x 12 + 10
Amount saved on Day 11
= 11 x 12 + 10
= $142
(b)
Number of days that Ivory takes to save $190
= (190 - 10) ÷ 12
= 180 ÷ 12
= 15
(c)
Total savings that Ivory saves by Day 15
= 22 + 34 + ... + 178 + 190
= (22 + 190) x (15 ÷ 2)
= 212 x 7.5
= $1590
Answer(s): (a) $142; (b) 15; (c) $1590
