PSLE Emma 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 $2 note in the box every 3 days. The total value of the savings after 132 days was $171.40.
- How many coins were there altogether?
- How many of the coins were 50¢ coins?
(a)
Total number of coins
= 2 x 132
= 264
(b)
Number of sets of 3 days
= 132 ÷ 3
= 44
Amount that her father put in
= 44 x 2
= $88
Amount that Emma saved by herself
= 171.40 - 88
= $83.40
Number of 50¢ |
Value of 50¢ |
Number of 20¢ |
Value of 20¢ |
Total value |
264 |
264 x 0.5 = 132 |
0 |
0 |
132 |
263 |
263 x 0.5 = 131.5 |
1 |
1 x 0.2 = 0.2 |
131.7 |
Small difference
= 132 - 131.7
= 0.3
Big difference
= 132 - 83.4
= 48.6
$1 = 100¢
$0.30 = 0.30 x 100 = 30¢
$48.60 = 48.60 x 100 = 4860¢
Number of 20¢ coins
= 4860 ÷ 30
= 162
Number of 50¢ coins
= 264 - 162
= 102
Answer(s): (a) 264; (b) 102