A can finish a job in 8 hours and B can finish the same job in 12 hours independently. If they work simultaneously, in how many hours can they do the same job?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 4.8.
A can finish the job = 8 hours
so¸ A's work rate of the job per hour = 1/8
B can finish the job = 12 hours
so B's work rate of the job per hour = 1/12
Combined work rate = 1/8 + 1/12 = 5/24
the time taken to complete the job = 1/(5/24) = 1 × 24/5 = 4.8 hours