Mary can do a piece of work in 28 days. Rosy is 40% more efficient than Mary. The number of days taken by Rosy to do the same piece of work is?  Choose the correct choice from the following choices:
A) 22 B) 24 C) 20 D) 25 E) 27
Ratio of times taken by Mary and Rosy = 140:100 = 14:10   Suppose Rosy takes x days to do the work.   14:10 :: 28:x =&gt; x= 20 days.   Hence, Rosy takes 20 days to complete the work.   Answer: 20
<result>C</result>
Mary can do a piece of work in 28 days. Rosy is 40% more efficient than Mary. The number of days taken by Rosy to do the same piece of work is?