-
A can do a work in 5 days less than the time taken by B to do it. If both of them together take
11 1 9
days, then the time taken by ‘B’ alone to do the same work (in days) is
-
- 15
- 20
- 25
- 30
Correct Option: C
Using Rule 2,
If the time taken by B to complete the work be x days, then
time taken by A = (x – 5) days
| ∴ | + | = | ||||
| x | x - 5 | 100 |
| ⇒ | = | |||
| x(x - 5) | 100 |
⇒ 9x2 – 45x = 200x –500
⇒ 9x2 – 245x + 500 = 0
⇒ 9x2 – 225x – 20x + 500 = 0
⇒ 9x (x – 25) – 20 (x – 25) = 0
⇒ (x – 25) (9x – 20) = 0
| ⇒ x = 25 because x ≠ | 9 |
