PSLE Emily started a savings plan by putting 2 coins into a money box every day. Each coin was either a 20¢ or 50¢ coin. Her aunt also put in $10 note in the box every 4 days. The total value of the savings after 148 days was $459.20.
- 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 4 days
= 148 ÷ 4
= 37
Amount that her aunt put in
= 37 x 10
= $370
Amount that Emily saved by herself
= 459.20 - 370
= $89.20
Number of 50¢ |
Value of 50¢ |
Number of 20¢ |
Value of 20¢ |
Total value |
296 |
296 x 0.5 = 148 |
0 |
0 |
148 |
295 |
295 x 0.5 = 147.5 |
1 |
1 x 0.2 = 0.2 |
147.7 |
Small difference
= 148 - 147.7
= 0.3
Big difference
= 148 - 89.2
= 58.8
$1 = 100¢
$0.30 = 0.30 x 100 = 30¢
$58.80 = 58.80 x 100 = 5880¢
Number of 20¢ coins
= 5880 ÷ 30
= 196
Number of 50¢ coins
= 296 - 196
= 100
Answer(s): (a) 296; (b) 100