Penelope was 7 years old last year. She was 22 years younger than Mary.
- How old will her Mary be 3 years later?
- In how many years' time will Penelope's age be 13 of Mary's age?
| |
Penelope |
Mary |
Difference |
| Before (Last year) |
7 |
29 |
22 |
| Change 1 |
+ 1 |
+ 1 |
|
| After 1 (Now) |
8 |
30 |
22 |
| Change 2 |
+ 3 |
+ 3 |
|
| After 2 (3 years later) |
|
? |
22 |
(a)
Mary's age this year
= 7 + 22
= 29
Mary's age this year
= 29 + 1
= 30
Mary's age in 3 years' time
= 30 + 3
= 33
| |
Penelope |
Mary |
Difference |
| Before |
8 |
30 |
22 |
| Change |
+ ? |
+ ? |
|
| After |
1 u |
3 u |
2 u |
(b)
The difference in the age between Penelope and Mary at first and in the end remains unchanged.
Difference in the age between Penelope and Mary
= 3 u - 1 u
= 2 u
2 u = 22
1 u = 22 ÷ 2 = 11
Number of years' time that Penelope's age be
13 of Mary's age
= 11 - 8
= 3
Answer(s): (a) 33; (b) 3
