The table shows how much Kathy saves daily. For each subsequent day, she saves $12 more than the previous day.
- How much will Kathy save on Day 9?
- On which day will Kathy save $178?
- How much savings will Kathy 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 9
= 9 x 12 + 10
= $118
(b)
Number of days that Kathy takes to save $178
= (178 - 10) ÷ 12
= 168 ÷ 12
= 14
(c)
Total savings that Kathy saves by Day 14
= 22 + 34 + ... + 166 + 178
= (22 + 178) x (14 ÷ 2)
= 200 x 7
= $1400
Answer(s): (a) $118; (b) 14; (c) $1400
