A can do a job in 8 days, B in 12 days. How long do A and B take working together?
- $10$ days
- $6$ days
- $4.8$ days
- $3.6$ days
Show answer and solution
Correct answer: C. $4.8$ days
Combined rate = 1/8 + 1/12 = 3/24 + 2/24 = 5/24. Time = 24/5 = 4.8 days.
*Shortcut: AB/(A+B) = 96/20 = 4.8.*