The table shows how much Gem saves daily. For each subsequent day, she saves $6 more than the previous day.
- How much will Gem save on Day 9?
- On which day will Gem save $112?
- How much savings will Gem have in total by the day found in part (b)?
(a)
Pattern for the amount saved
Day 1: 1 x 6 + 10 = $16
Day 2: 2 x 6 + 10 = $22
Day 3: 3 x 6 + 10 = $28
Day 4: 4 x 6 + 10 = $34
Formula
Amount saved = Day Number x 6 + 10
Amount saved on Day 9
= 9 x 6 + 10
= $64
(b)
Number of days that Gem takes to save $112
= (112 - 10) ÷ 6
= 102 ÷ 6
= 17
(c)
Total savings that Gem saves by Day 17
= 16 + 22 + ... + 106 + 112
= (16 + 112) x (17 ÷ 2)
= 128 x 8.5
= $1088
Answer(s): (a) $64; (b) 17; (c) $1088
