| 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 [SSC (CGL) Mains 2015] |
A) 15
B) 10
C) 8
D) 12
Correct Answer: B
Solution :
| Work done by P and Q in 6 days |
| \[=6\times \frac{7}{60}=\frac{7}{10}\] |
| \[\therefore \]Remaining \[=1-\frac{7}{10}=\frac{3}{10}th\] of work done by P in 3 days. |
| Since, P alone can do the work in 10 days. |
| \[\therefore \] Q alone can do the work in \[\frac{10\times 6}{10-6}=15\,days\] |
| \[\therefore \] R alone can do the work in \[\frac{15\times \frac{60}{7}}{15-\frac{60}{7}}=20\,days\] |
| \[\therefore \] Difference \[=20-10=10\text{ }days\] |
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