PSLE Nicole started a savings plan by putting 2 coins into a money box every day. Each coin was either a 10¢ or 50¢ coin. Her mother also put in $2 note in the box every 3 days. The total value of the savings after 183 days was $209.80.
- How many coins were there altogether?
- How many of the coins were 50¢ coins?
(a)
Total number of coins
= 2 x 183
= 366
(b)
Number of sets of 3 days
= 183 ÷ 3
= 61
Amount that her mother put in
= 61 x 2
= $122
Amount that Nicole saved by herself
= 209.80 - 122
= $87.80
Number of 50¢ |
Value of 50¢ |
Number of 10¢ |
Value of 10¢ |
Total value |
366 |
366 x 0.5 = 183 |
0 |
0 |
183 |
365 |
365 x 0.5 = 182.5 |
1 |
1 x 0.1 = 0.1 |
182.6 |
Small difference
= 183 - 182.6
= 0.4
Big difference
= 183 - 87.8
= 95.2
$1 = 100¢
$0.40 = 0.40 x 100 = 40¢
$95.20 = 95.20 x 100 = 9520¢
Number of 10¢ coins
= 9520 ÷ 40
= 238
Number of 50¢ coins
= 366 - 238
= 128
Answer(s): (a) 366; (b) 128