P and Q can complete a job in 4 days and 12 days, respectively. They work on alternate days with P starting the job. In how many days will the job be completed?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. 6 days.
Total work = 12 (LCM of 4 and 12)
Efficiency of P = 12/4 = 3
Efficiency of Q = 12/12 = 1
In 2 days, P and Q complete the work = 3 + 1 = 4
Total time required = (12/4) × 2 = 3 × 2 = 6 days