The table shows how much Eva saves daily. For each subsequent day, she saves $8 more than the previous day.
- How much will Eva save on Day 10?
- On which day will Eva save $138?
- How much savings will Eva 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 10
= 10 x 8 + 10
= $90
(b)
Number of days that Eva takes to save $138
= (138 - 10) ÷ 8
= 128 ÷ 8
= 16
(c)
Total savings that Eva saves by Day 16
= 18 + 26 + ... + 130 + 138
= (18 + 138) x (16 ÷ 2)
= 156 x 8
= $1248
Answer(s): (a) $90; (b) 16; (c) $1248
