The table shows how much Roshel saves daily. For each subsequent day, she saves $3 more than the previous day.
- How much will Roshel save on Day 5?
- On which day will Roshel save $70?
- How much savings will Roshel have in total by the day found in part (b)?
(a)
Pattern for the amount saved
Day 1: 1 x 3 + 10 = $13
Day 2: 2 x 3 + 10 = $16
Day 3: 3 x 3 + 10 = $19
Day 4: 4 x 3 + 10 = $22
Formula
Amount saved = Day Number x 3 + 10
Amount saved on Day 5
= 5 x 3 + 10
= $25
(b)
Number of days that Roshel takes to save $70
= (70 - 10) ÷ 3
= 60 ÷ 3
= 20
(c)
Total savings that Roshel saves by Day 20
= 13 + 16 + ... + 67 + 70
= (13 + 70) x (20 ÷ 2)
= 83 x 10
= $830
Answer(s): (a) $25; (b) 20; (c) $830
