PSLE Hilda started a savings plan by putting 2 coins into a money box every day. Each coin was either a 10¢ or 50¢ coin. Her aunt also put in $5 note in the box every 3 days. The total value of the savings after 129 days was $283.60.
- How many coins were there altogether?
- How many of the coins were 50¢ coins?
(a)
Total number of coins
= 2 x 129
= 258
(b)
Number of sets of 3 days
= 129 ÷ 3
= 43
Amount that her aunt put in
= 43 x 5
= $215
Amount that Hilda saved by herself
= 283.60 - 215
= $68.60
Number of 50¢ |
Value of 50¢ |
Number of 10¢ |
Value of 10¢ |
Total value |
258 |
258 x 0.5 = 129 |
0 |
0 |
129 |
257 |
257 x 0.5 = 128.5 |
1 |
1 x 0.1 = 0.1 |
128.6 |
Small difference
= 129 - 128.6
= 0.4
Big difference
= 129 - 68.6
= 60.4
$1 = 100¢
$0.40 = 0.40 x 100 = 40¢
$60.40 = 60.40 x 100 = 6040¢
Number of 10¢ coins
= 6040 ÷ 40
= 151
Number of 50¢ coins
= 258 - 151
= 107
Answer(s): (a) 258; (b) 107