PSLE Nora started a savings plan by putting 2 coins into a money box every day. Each coin was either a 10¢ or 50¢ coin. Her mother also put in $2 note in the box every 2 days. The total value of the savings after 148 days was $234.40.
- How many coins were there altogether?
- How many of the coins were 50¢ coins?
(a)
Total number of coins
= 2 x 148
= 296
(b)
Number of sets of 2 days
= 148 ÷ 2
= 74
Amount that her mother put in
= 74 x 2
= $148
Amount that Nora saved by herself
= 234.40 - 148
= $86.40
Number of 50¢ |
Value of 50¢ |
Number of 10¢ |
Value of 10¢ |
Total value |
296 |
296 x 0.5 = 148 |
0 |
0 |
148 |
295 |
295 x 0.5 = 147.5 |
1 |
1 x 0.1 = 0.1 |
147.6 |
Small difference
= 148 - 147.6
= 0.4
Big difference
= 148 - 86.4
= 61.6
$1 = 100¢
$0.40 = 0.40 x 100 = 40¢
$61.60 = 61.60 x 100 = 6160¢
Number of 10¢ coins
= 6160 ÷ 40
= 154
Number of 50¢ coins
= 296 - 154
= 142
Answer(s): (a) 296; (b) 142