PSLE Zoe started a savings plan by putting 2 coins into a money box every day. Each coin was either a 20¢ or 50¢ coin. Her father also put in $5 note in the box every 5 days. The total value of the savings after 110 days was $194.80.
- How many coins were there altogether?
- How many of the coins were 50¢ coins?
(a)
Total number of coins
= 2 x 110
= 220
(b)
Number of sets of 5 days
= 110 ÷ 5
= 22
Amount that her father put in
= 22 x 5
= $110
Amount that Zoe saved by herself
= 194.80 - 110
= $84.80
Number of 50¢ |
Value of 50¢ |
Number of 20¢ |
Value of 20¢ |
Total value |
220 |
220 x 0.5 = 110 |
0 |
0 |
110 |
219 |
219 x 0.5 = 109.5 |
1 |
1 x 0.2 = 0.2 |
109.7 |
Small difference
= 110 - 109.7
= 0.3
Big difference
= 110 - 84.8
= 25.2
$1 = 100¢
$0.30 = 0.30 x 100 = 30¢
$25.20 = 25.20 x 100 = 2520¢
Number of 20¢ coins
= 2520 ÷ 30
= 84
Number of 50¢ coins
= 220 - 84
= 136
Answer(s): (a) 220; (b) 136