PSLE Dana 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 2 days. The total value of the savings after 174 days was $286.20.
- How many coins were there altogether?
- How many of the coins were 50¢ coins?
(a)
Total number of coins
= 2 x 174
= 348
(b)
Number of sets of 2 days
= 174 ÷ 2
= 87
Amount that her father put in
= 87 x 2
= $174
Amount that Dana saved by herself
= 286.20 - 174
= $112.20
Number of 50¢ |
Value of 50¢ |
Number of 20¢ |
Value of 20¢ |
Total value |
348 |
348 x 0.5 = 174 |
0 |
0 |
174 |
347 |
347 x 0.5 = 173.5 |
1 |
1 x 0.2 = 0.2 |
173.7 |
Small difference
= 174 - 173.7
= 0.3
Big difference
= 174 - 112.2
= 61.8
$1 = 100¢
$0.30 = 0.30 x 100 = 30¢
$61.80 = 61.80 x 100 = 6180¢
Number of 20¢ coins
= 6180 ÷ 30
= 206
Number of 50¢ coins
= 348 - 206
= 142
Answer(s): (a) 348; (b) 142