The table shows how much Yoko saves daily. For each subsequent day, she saves $8 more than the previous day.
- How much will Yoko save on Day 12?
- On which day will Yoko save $90?
- How much savings will Yoko have in total by the day found in part (b)?
(a)
Pattern for the amount saved
Day 1: 1 x 8 + 10 = $18
Day 2: 2 x 8 + 10 = $26
Day 3: 3 x 8 + 10 = $34
Day 4: 4 x 8 + 10 = $42
Formula
Amount saved = Day Number x 8 + 10
Amount saved on Day 12
= 12 x 8 + 10
= $106
(b)
Number of days that Yoko takes to save $90
= (90 - 10) ÷ 8
= 80 ÷ 8
= 10
(c)
Total savings that Yoko saves by Day 10
= 18 + 26 + ... + 82 + 90
= (18 + 90) x (10 ÷ 2)
= 108 x 5
= $540
Answer(s): (a) $106; (b) 10; (c) $540
