PSLE Kimberly 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 $2 note in the box every 2 days. The total value of the savings after 104 days was $189.40.
- How many coins were there altogether?
- How many of the coins were 50¢ coins?
(a)
Total number of coins
= 2 x 104
= 208
(b)
Number of sets of 2 days
= 104 ÷ 2
= 52
Amount that her aunt put in
= 52 x 2
= $104
Amount that Kimberly saved by herself
= 189.40 - 104
= $85.40
Number of 50¢ |
Value of 50¢ |
Number of 20¢ |
Value of 20¢ |
Total value |
208 |
208 x 0.5 = 104 |
0 |
0 |
104 |
207 |
207 x 0.5 = 103.5 |
1 |
1 x 0.2 = 0.2 |
103.7 |
Small difference
= 104 - 103.7
= 0.3
Big difference
= 104 - 85.4
= 18.6
$1 = 100¢
$0.30 = 0.30 x 100 = 30¢
$18.60 = 18.60 x 100 = 1860¢
Number of 20¢ coins
= 1860 ÷ 30
= 62
Number of 50¢ coins
= 208 - 62
= 146
Answer(s): (a) 208; (b) 146