The table shows how much Nora saves daily. For each subsequent day, she saves $4 more than the previous day.
- How much will Nora save on Day 11?
- On which day will Nora save $130?
- How much savings will Nora 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 Nora takes to save $130
= (130 - 10) ÷ 4
= 120 ÷ 4
= 30
(c)
Total savings that Nora saves by Day 30
= 14 + 18 + ... + 126 + 130
= (14 + 130) x (30 ÷ 2)
= 144 x 15
= $2160
Answer(s): (a) $54; (b) 30; (c) $2160