Multiple choice general knowledge math & puzzles

Ram, who is half as efficient as Krish, will take 24 days to complete a work if he worked alone. If Ram and Krish worked together, how long will they take to complete the work?

  1. 8

  2. 16

  3. 6

  4. 12

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ram takes 24 days alone, so Ram's rate = 1/24 work/day. Krish is twice as efficient, so Krish's rate = 1/12 work/day. Together: 1/24 + 1/12 = 1/24 + 2/24 = 3/24 = 1/8 work/day. Time = 1/(1/8) = 8 days. Option B (16) is Ram's time alone - a common error of not combining rates.