Sapna finishes a job in 12 hours working alone. If Sapna and Riya finish the same job in 8 hours working together at their respective constant rates, then, in how many hours can Riya do the job working alone?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 24.
Total work = 24 (LCM of 12 and 8)
Efficiency of Sapna = 24/12 = 2
Efficiency of Sapna and Riya = 24/8 = 3
Efficiency of Riya = 3 - 2 = 1
Time required for Riya = 24/1 = 24 days
Therefore, Riya can do the job in 24 days.