Mike is 50% less efficient than Alice. How much time will they, working together, take to complete a job which Alice alone could have done in 15 days? Choose the correct choice from the following choices:  A) 5 days  B) 10 days  C) 9 days  D) 18 days  E) 15 days
Ratio of times taken by Alice and Mike = 100 : 150 = 2 : 3.   Suppose Mike takes x days to do the work.   Then, 2 : 3 : : 15 : x â‡’ x = (15Ã—3)/2 â‡’ x = 45â„2   Aliceâ€™s 1 dayâ€™s work = 1â„15; Mikeâ€™s 1 days work = 2â„45   (Alice + Mike)â€™s 1 dayâ€™s work = (1â„15 + 2â„45) = 1â„9   âˆ´ Alice and Mike together can complete the job in 9 days.   Answer 9 days
<result>C</result>
Mike is 50% less efficient than Alice. How much time will they, working together, take to complete a job which Alice alone could have done in 15 days?