PSLE Wendy started a savings plan by putting 2 coins into a money box every day. Each coin was either a 20¢ or 50¢ coin. Her mother also put in $5 note in the box every 4 days. The total value of the savings after 108 days was $217.20.
- How many coins were there altogether?
- How many of the coins were 50¢ coins?
(a)
Total number of coins
= 2 x 108
= 216
(b)
Number of sets of 4 days
= 108 ÷ 4
= 27
Amount that her mother put in
= 27 x 5
= $135
Amount that Wendy saved by herself
= 217.20 - 135
= $82.20
Number of 50¢ |
Value of 50¢ |
Number of 20¢ |
Value of 20¢ |
Total value |
216 |
216 x 0.5 = 108 |
0 |
0 |
108 |
215 |
215 x 0.5 = 107.5 |
1 |
1 x 0.2 = 0.2 |
107.7 |
Small difference
= 108 - 107.7
= 0.3
Big difference
= 108 - 82.2
= 25.8
$1 = 100¢
$0.30 = 0.30 x 100 = 30¢
$25.80 = 25.80 x 100 = 2580¢
Number of 20¢ coins
= 2580 ÷ 30
= 86
Number of 50¢ coins
= 216 - 86
= 130
Answer(s): (a) 216; (b) 130