PSLE Jaslyn 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 $10 note in the box every 2 days. The total value of the savings after 190 days was $1069.80.
- How many coins were there altogether?
- How many of the coins were 50¢ coins?
(a)
Total number of coins
= 2 x 190
= 380
(b)
Number of sets of 2 days
= 190 ÷ 2
= 95
Amount that her father put in
= 95 x 10
= $950
Amount that Jaslyn saved by herself
= 1069.80 - 950
= $119.80
Number of 50¢ |
Value of 50¢ |
Number of 20¢ |
Value of 20¢ |
Total value |
380 |
380 x 0.5 = 190 |
0 |
0 |
190 |
379 |
379 x 0.5 = 189.5 |
1 |
1 x 0.2 = 0.2 |
189.7 |
Small difference
= 190 - 189.7
= 0.3
Big difference
= 190 - 119.8
= 70.2
$1 = 100¢
$0.30 = 0.30 x 100 = 30¢
$70.20 = 70.20 x 100 = 7020¢
Number of 20¢ coins
= 7020 ÷ 30
= 234
Number of 50¢ coins
= 380 - 234
= 146
Answer(s): (a) 380; (b) 146