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P and Q together can do a job in 6 days. Q and R can finish the same job in 60/7 days. P started the work and worked for 3 days. Q and R continued for 6 days. Then the difference of days in which R and P can complete the job is
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- 15
- 10
- 8
- 12
Correct Option: B
| (P + Q)’s 1 day’s work = | 6 |
| (Q + R)’s 1 day’s work = | 60 |
Let P alone do the work in x days.
According to the question.
| = | + | = 1 | ||
| x | 60 |
| ⇒ | = 1 - | = | ||||
| x | 10 | 10 |
⇒ x = 10 days
∴ Q’s 1 day’s work
| ⇒ | - | = | = | |||||
| 6 | 10 | 30 | 15 |
R’s 1 day’s work
| ⇒ | - | = | = | |||||
| 60 | 15 | 60 | 20 |
∴ Time taken by R = 20 days
∴ Required answer = 20 – 10 = 10 days
