Cathy was 10 years old last year. She was 24 years younger than Zoe.
- How old will her Zoe be 8 years later?
- In how many years' time will Cathy's age be 13 of Zoe's age?
| |
Cathy |
Zoe |
Difference |
| Before (Last year) |
10 |
34 |
24 |
| Change 1 |
+ 1 |
+ 1 |
|
| After 1 (Now) |
11 |
35 |
24 |
| Change 2 |
+ 8 |
+ 8 |
|
| After 2 (8 years later) |
|
? |
24 |
(a)
Zoe's age this year
= 10 + 24
= 34
Zoe's age this year
= 34 + 1
= 35
Zoe's age in 8 years' time
= 35 + 8
= 43
| |
Cathy |
Zoe |
Difference |
| Before |
11 |
35 |
24 |
| Change |
+ ? |
+ ? |
|
| After |
1 u |
3 u |
2 u |
(b)
The difference in the age between Cathy and Zoe at first and in the end remains unchanged.
Difference in the age between Cathy and Zoe
= 3 u - 1 u
= 2 u
2 u = 24
1 u = 24 ÷ 2 = 12
Number of years' time that Cathy's age be
13 of Zoe's age
= 12 - 11
= 1
Answer(s): (a) 43; (b) 1
