31.

A man can do a piece of work in 5 days, but with the help of his son he can do it in 3 days. In what time can the son do it alone ?

 A. [Math Processing Error] B. [Math Processing Error] C. [Math Processing Error] D. [Math Processing Error]
Explanation: In this type of question, where we have one person work and together work done. Then we can easily get the other person work just by subtracting them. As, Son's one day work = [Math Processing Error] So son will do whole work in 15/2 days which is = [Math Processing Error]

32.

A can do a job in 16 days, B can do same job in 12 days. With the help of C they did the job in 4 days. C alone can do the same job in how many days ?

 A. 6 1 2 days B. 7 1 2 days C. 8 3 5 days D. 9 3 5 days
Explanation: In this question we having, A's work, B's work and A+B+C work. We need to calculate C's work. We can do it by, (A+B+C)'s work - (A's work + B's work). Let's solve it now: C's 1 day work = 1 4 −( 1 16 + 1 12 ) =( 1 4 − 7 48 ) = 5 48 So C can alone finish the job in 48/5 days, Which is = 9 3 5 days

33.

To complete a work A and B takes 8 days, B and C takes 12 days, A,B and C takes 6 days. How much time A and C will take

 A. 24 days B. 16 days C. 12 days D. 8 days
Explanation: A+B 1 day work = 1/8 B+C 1 day work = 1/12 A+B+C 1 day work = 1/6 We can get A work by (A+B+C)-(B+C) And C by (A+B+C)-(A+B) So A 1 day work = 1 6 − 1 12 = 1 12 Similarly C 1 day work = 1 6 − 1 8 = 4−3 24 = 1 24 So A and C 1 day work = 1 12 + 1 24 = 3 24 = 1 8 So A and C can together do this work in 8 days

34.

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. 40 days B. 35 days C. 30 days D. 25 days