PSLE Hilda started a savings plan by putting 2 coins into a money box every day. Each coin was either a 20¢ or 50¢ coin. Her uncle also put in $2 note in the box every 2 days. The total value of the savings after 126 days was $207.30.
- How many coins were there altogether?
- How many of the coins were 50¢ coins?
(a)
Total number of coins
= 2 x 126
= 252
(b)
Number of sets of 2 days
= 126 ÷ 2
= 63
Amount that her uncle put in
= 63 x 2
= $126
Amount that Hilda saved by herself
= 207.30 - 126
= $81.30
Number of 50¢ |
Value of 50¢ |
Number of 20¢ |
Value of 20¢ |
Total value |
252 |
252 x 0.5 = 126 |
0 |
0 |
126 |
251 |
251 x 0.5 = 125.5 |
1 |
1 x 0.2 = 0.2 |
125.7 |
Small difference
= 126 - 125.7
= 0.3
Big difference
= 126 - 81.3
= 44.7
$1 = 100¢
$0.30 = 0.30 x 100 = 30¢
$44.70 = 44.70 x 100 = 4470¢
Number of 20¢ coins
= 4470 ÷ 30
= 149
Number of 50¢ coins
= 252 - 149
= 103
Answer(s): (a) 252; (b) 103