The table shows how much Zara saves daily. For each subsequent day, she saves $4 more than the previous day.
- How much will Zara save on Day 11?
- On which day will Zara save $62?
- How much savings will Zara have in total by the day found in part (b)?
(a)
Pattern for the amount saved
Day 1: 1 x 4 + 10 = $14
Day 2: 2 x 4 + 10 = $18
Day 3: 3 x 4 + 10 = $22
Day 4: 4 x 4 + 10 = $26
Formula
Amount saved = Day Number x 4 + 10
Amount saved on Day 11
= 11 x 4 + 10
= $54
(b)
Number of days that Zara takes to save $62
= (62 - 10) ÷ 4
= 52 ÷ 4
= 13
(c)
Total savings that Zara saves by Day 13
= 14 + 18 + ... + 58 + 62
= (14 + 62) x (13 ÷ 2)
= 76 x 6.5
= $494
Answer(s): (a) $54; (b) 13; (c) $494