The table shows how much Nora saves daily. For each subsequent day, she saves $7 more than the previous day.
- How much will Nora save on Day 12?
- On which day will Nora save $143?
- How much savings will Nora have in total by the day found in part (b)?
(a)
Pattern for the amount saved
Day 1: 1 x 7 + 10 = $17
Day 2: 2 x 7 + 10 = $24
Day 3: 3 x 7 + 10 = $31
Day 4: 4 x 7 + 10 = $38
Formula
Amount saved = Day Number x 7 + 10
Amount saved on Day 12
= 12 x 7 + 10
= $94
(b)
Number of days that Nora takes to save $143
= (143 - 10) ÷ 7
= 133 ÷ 7
= 19
(c)
Total savings that Nora saves by Day 19
= 17 + 24 + ... + 136 + 143
= (17 + 143) x (19 ÷ 2)
= 160 x 9.5
= $1520
Answer(s): (a) $94; (b) 19; (c) $1520