The ratio of Peter's age to Luis's age is 3 : 1. Last year, their average age was 11. How old will Luis be in 11 years' time?
| |
Peter |
Luis |
Total |
| Before |
3 u - 1 |
1 u - 1 |
22 |
| Change |
+ 1 |
+ 1 |
|
| After |
3 u |
1 u |
24 |
Total age of Peter and Luis this year
= 3 u + 1 u
= 4 u
Total age of Peter and Luis this year
= 2 x 11 + 1 + 1
= 22 + 2
= 24
4 u = 24
1 u = 24 ÷ 4 = 6
Luis's age in 11 years' time
= 1 u + 11
= 1 x 6 + 11
= 6 + 11
= 17
Answer(s): 17
