The table shows how much Mary saves daily. For each subsequent day, she saves $7 more than the previous day.
- How much will Mary save on Day 10?
- On which day will Mary save $192?
- How much savings will Mary 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 10
= 10 x 7 + 10
= $80
(b)
Number of days that Mary takes to save $192
= (192 - 10) ÷ 7
= 182 ÷ 7
= 26
(c)
Total savings that Mary saves by Day 26
= 17 + 24 + ... + 185 + 192
= (17 + 192) x (26 ÷ 2)
= 209 x 13
= $2717
Answer(s): (a) $80; (b) 26; (c) $2717
