The ratio of Bobby's age to Jack's age is 6 : 1. Last year, their average age was 13. How old will Jack be in 11 years' time?
| |
Bobby |
Jack |
Total |
| Before |
6 u - 1 |
1 u - 1 |
26 |
| Change |
+ 1 |
+ 1 |
|
| After |
6 u |
1 u |
28 |
Total age of Bobby and Jack this year
= 6 u + 1 u
= 7 u
Total age of Bobby and Jack this year
= 2 x 13 + 1 + 1
= 26 + 2
= 28
7 u = 28
1 u = 28 ÷ 7 = 4
Jack's age in 11 years' time
= 1 u + 11
= 1 x 4 + 11
= 4 + 11
= 15
Answer(s): 15
