Tammy had 50 coins.
25 were red and the rest were blue and pink. The ratio of the number of blue coins to the number of pink coins was 1 : 4. Tammy decided to buy some more red coins to increase the number of red coins to half of the total number of coins.
- How many less blue coins than red coins did he have at first?
- How many more red coins did he have to buy?
| Red coins |
Blue coins |
Pink coins |
Total |
| 2x5 |
3x5 |
|
| |
1x3 |
4x3 |
|
| 10 u |
3 u |
12 u |
50 |
| |
Red coins |
Blue coins |
Pink coins |
| Before |
10 u |
3 u |
12 u |
| Change |
+ ? |
|
|
| After |
15 u |
15 u |
Comparing red, blue
and pink coins
in the end |
1 |
1 |
(a)
The total number of blue coins and pink coins is repeated. Make the total number of blue coins and pink coins the same. LCM of 3 and 5 is 15.
Total number of coins at first
= 10 u + 3 u + 12 u
= 25 u
25 u = 50
1 u = 50 ÷ 25 = 2
Number of less blue coins than red coins at first
= 10 u - 3 u
= 7 u
= 7 x 2
= 14
(b)
Number of more red coins that Tammy had to buy
= 15 u - 10 u
= 5 u
= 5 x 2
= 10
Answer(s): (a) 14; (b) 10
