P is twice as efficient as Q. Q takes 12 days to complete a job. If both of them work together, how much time will they take to complete the job?

P is twice as efficient as Q. Q takes 12 days to complete a job. If both of them work together, how much time will they take to complete the job?
1). 6 days
2). 5 days
3). 4 days
4). 3 days

Time taken by Q to complete a job = 12 days

P is twice as efficient.

∴ Time taken by P to complete the job = 12/2 = 6 days

Work done by Q in 1 day = 1/12

Work done by P in 1 day = 1/6

Work done in 1 day = 1/12 + 1/6 = 3/12 = ¼

∴ Time taken by to complete the work together = 4 days.

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