PSLE Fanny started a savings plan by putting 2 coins into a money box every day. Each coin was either a 10¢ or 50¢ coin. Her father also put in $10 note in the box every 3 days. The total value of the savings after 117 days was $463.80.
- How many coins were there altogether?
- How many of the coins were 50¢ coins?
(a)
Total number of coins
= 2 x 117
= 234
(b)
Number of sets of 3 days
= 117 ÷ 3
= 39
Amount that her father put in
= 39 x 10
= $390
Amount that Fanny saved by herself
= 463.80 - 390
= $73.80
Number of 50¢ |
Value of 50¢ |
Number of 10¢ |
Value of 10¢ |
Total value |
234 |
234 x 0.5 = 117 |
0 |
0 |
117 |
233 |
233 x 0.5 = 116.5 |
1 |
1 x 0.1 = 0.1 |
116.6 |
Small difference
= 117 - 116.6
= 0.4
Big difference
= 117 - 73.8
= 43.2
$1 = 100¢
$0.40 = 0.40 x 100 = 40¢
$43.20 = 43.20 x 100 = 4320¢
Number of 10¢ coins
= 4320 ÷ 40
= 108
Number of 50¢ coins
= 234 - 108
= 126
Answer(s): (a) 234; (b) 126