If John can complete a job in 8 hours and Sara can complete the same job in 12 hours how long will it take them to complete the job together ?
A5 hours
B6⅔ hours
C4⅘ hours
D7½ hours
Answer:
C. 4⅘ hours
Read Explanation:
total work = lcm(8, 12) = 24
efficiency of John = 24/8 = 3
efficiency of Sara = 24/12 = 2
efficiency of John and Sarah together = 3 + 2 = 5
the time taken by Sara and join to complete the job together
= total work / efficiency
= 24/5
= 4⅘