Tuesday, 9 February 2016

A does half as much work as B in three-fourth of the time. If together they take 18 days to complete the work, how much time shall B take to do it?



A does half as much work as B in three-fourth of the time. If together they take 18 days to complete the work, how much time shall B take to do it?

(A) 30 days

(B) 35 days

(C) 40 days

(D) None of these

Solution:
1.  Let B does the work in B days, then B in 1 day will do 1/B part of work
2.  A takes three-fourth of working days of B to do half of work done by B, therefore A in 3/4XB days will do 1/2 work, then in 1 day A would do 1/2÷3/4XB=2/3B part of work
3.  A and B together in 1 day will do =1/B+2/3B=5/3B part of work
4.  As given, A and B do 1 work in 18days, then A and B together in 1 day will do 1/18 part of the work
5.  Therefore, looking at step 3 and 4 ,5/3B=1/18, THEN B=30DAYS (Answer)

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