1. X can do 1/4 of a work in 10 days, Y can do 40% of the work in 40 days and Z can do 1/3 of the work in 13 days. Who will complete the work first?

A. X B. Y C. Z D. X and Z both

Answer Answer: Option C Explanation: Whole work will be done by X in (10*4) = 40 days.
Whole work will be done by Y in (40*100/40) = 100 days.
Whole work will be done by Z in (13*3) = 39 days.
Therefore Z will complete the work first.

2. A and B undertake to do a piece of work for Rs.600. A alone can do it in 6 days while B alone can do it in 8 days. With the help of C they finish it in 3 days.Find the share of each?

A. Rs.65 B. Rs.68 C. Rs.75 D. Rs.70

Answer Answer: Option C Explanation: C's 1 day's work = 1/3 - (1/6 + 1/ 8) = 1/24
A: B : C = ratio of their 1 day's work = 1/6: 1/8 : 1/24 = 4 : 3: 1
A's share = Rs.(600 * 4/8) = Rs.300, B's share = Rs.(600*3/8) = Rs.225
C's share = Rs.[(600-(300+225)] = Rs.75

3. A man can do a job in 15 days. His father takes 20 days and his son finishes it in 25 days. How long will they take to complete the job if they all work together?

A. Less than 6 days B. Exactly 6 days C. Approximately 6.4 days D. More than 10 days

Answer Answer: Option C Explanation: 1 day's work of the three persons = (1/15+ 1/20+1/25) = 47/300.
so, all the three together will complete the work in 300/47 = 6.4 days.

4. A and B can do a piece of work in 5 days; B and C can do it in 7 days; A and C can do it in 4 days. who among these will take the least time if put to do it alone?

A. B B. C C. A D. data inadequate

Answer Answer: Option C Explanation: (A+B)'s 1 day's work = 1/5; (B+C)'s 1 day's work = 1/7; (A+C)'s 1 day's work =1/4.
Adding, we get : 2 (A + B + C) 's 1 day's work = (1/5 + 1/7 + 1/4) = 83/140.
(A+B+C)'s 1 day's work = 83/280.
A's 1 day's work = (83/280 - 1/7) = 43/280; B's 1 day's work = (83/280 - 1/4) = 13/280;
C's 1 day's work = (83/280 - 1/5) =27/280.
Thus time taken by A,B,C is 280/43 day's, 280/13 day's, 280/27 days respectively.
Clearly, the time taken by A is least.

5. A can lay railway track between two given stations in 16 days and B can do the same job in 12 days. With the help of C, they did the job in 4 days only. Then, C alone can do the job in

A. 9 1/5 days B. 9 2/5 days C. 9 3/5 days D. 10 days

Answer Answer: Option C Explanation: (A+B+C)'s 1 day's work = 1/4, A's 1 day's work = 1/16, B's 1 day's work = 1/12
therefore C's 1 day's work = 1/4 - ( 1/16+ 1/12) = (1/4 - 7/48) = 5/48.
so, c alone can do the work in 48/5 = 9 3/5 days.