The table shows how much Barbara saves daily. For each subsequent day, she saves $3 more than the previous day.
- How much will Barbara save on Day 10?
- On which day will Barbara save $163?
- How much savings will Barbara 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 10
= 10 x 3 + 10
= $40
(b)
Number of days that Barbara takes to save $163
= (163 - 10) ÷ 3
= 153 ÷ 3
= 51
(c)
Total savings that Barbara saves by Day 51
= 13 + 16 + ... + 160 + 163
= (13 + 163) x (51 ÷ 2)
= 176 x 25.5
= $4488
Answer(s): (a) $40; (b) 51; (c) $4488