**831. P and Q can complete a work in 20 days and 12 days respectively. P alone started the work and Q joined him after 4 days till the completion of the work. How long did the work last?**

A. 5 days**B. 10 days**

C. 15 days

D. 12 days

**Explanation:****Work done by P in 1 day = 1/20****Work done by Q in 1 day = 1/12****Work done by P in 4 days = 4 × (1/20) = 1/5****Remaining work = 1 – 1/5 = 4/5****Work done by P and Q in 1 day = 1/20 + 1/12 = 8/60 = 2/15****Number of days P and Q take to complete the remaining work = (4/5) / (2/15) = 6****Total days = 4 + 6 = 10**

**832. P can finish a work in 18 days. Q can finish the same work in 15 days. Q worked for 10 days and left the job. how many days does P alone need to finish the remaining work?**

A. 8**B. 6**

C. 4

D. 2

**Explanation:****Work done by P in 1 day = 1/18****Work done by Q in 1 day = 1/15****Work done by Q in 10 days = 10/15 = 2/3****Remaining work = 1 – 2/3 = 1/3****Number of days in which P can finish the remaining work = (1/3) / (1/18) = 6**

**833. P can lay railway track between two stations in 16 days. Q can do the same job in 12 days. With the help of R, they completes the job in 4 days. How much days does it take for R alone to complete the work?****A. 9(3/5) days**

B. 9(1/5) days

C. 9(2/5) days

D. 10 days

**Explanation:****Amount of work P can do in 1 day = 1/16****Amount of work Q can do in 1 day = 1/12****Amount of work P, Q and R can together do in 1 day = 1/4****Amount of work R can do in 1 day = 1/4 – (1/16 + 1/12) = 3/16 – 1/12 = 5/48****=> Hence R can do the job on 48/5 days = 9 (3/5) days**

**834. wo pipes X and Y fill a tank in 15 hrs. and 20 hrs. respectively, while a third pipe ‘Z’ can empty the full tank in 25 hrs. All the three pipes are opened in the beginning. After 10 hrs. Z is closed. In how much time, will the tank be full ?****A. 12 hrs**

B. 14 hrs

C. 16 hrs

D. 18 hrs

**Explanation:****Part filled in 10 hrs.****= 10[1/15+1/20−1/25]=23/30**

**835. 8 men can dig a pit in 20 days. If a man works half as much again as a boy, then 4 men and 9 boys can dig a similar pit in:__________?**

A. 12 days**B. 16 days**

C. 18 days

D. 20 days

**836. Efficiency of Rashid and Danish are in the ratio 5:8. If Danish takes 51 days less than Rashid to complete the work, find the time taken by Rashid to complete the work.**

A. 85 days

B. 126 days

C. 118 days**D. 136 days**

**Explanation:****Time taken is inversely proportional to their efficiency. So, time taken is in the ratio 8:5. Time taken by Rashid to finish the work = 8x Time taken by Danish to finish the work = 5x 8x-5x=51 3x=51 x=17 8x=136**

**837. If 12 men work 8 hours a day to complete a work in 10 days, how many men working 12 hours a day can complete the work in 5 days?****A. 16**

B. 4

C. 12

D. 8

**Explanation:****12 men work 8 hours for 10 days x men work 12 hours for 5 days x = (12*8*10)/(12*5) = 16 men**

**838. If daily wages of a man is double to that of a woman, how many men should work for 25 days to earn Rs.14400? Given that wages for 40 women for 30 days are Rs.21600.**

A. 15

B. 14**C. 16**

D. 13

**839. Mansoor-Ul-Haque and Aaqib are working on a special assignment. Mansoor-Ul-Haque needs 6 hours to type 32 pages on a computer and Aaqib needs 5 hours to type 40 pages. If both of them work together on two different computers, how much time is needed to type an assignment of 110 pages?**

A. 7 hour 15 minutes

B. 7 hour 30 minutes**C. 8 hour 15 minutes**

D. 8 hour 30 minutes

**Explanation:****Pages typed by Mansoor-Ul-Haque in 1 hour = 32/6 = 16/3****Pages typed by Aaqib in 1 hour = 40/5 = 8****Pages typed by Mansoor-Ul-Haque and Aaqib in 1 hour = 16/3 + 8 = 40/3****Time taken to type 110 pages when Mansoor-Ul-Haque and Aaqib work together = 110 × 3 /40 = 33/4****= 8 ¼ hours = 8 hour 15 minutes**

**840. Machine P can print one lakh books in 8 hours. Machine Q can print the same number of books in 10 hours while machine R can print the same in 12 hours. All the machines started printing at 9 A.M. Machine P is stopped at 11 A.M. and the remaining two machines complete work. Approximately at what time will the printing of one lakh books be completed?**

A. 3 pm

B. 2 pm**C. 1:00 pm**

D. 11 am

**Explanation:****Work done by P in 1 hour = 1/8****Work done by Q in 1 hour = 1/10****Work done by R in 1 hour = 1/12****Work done by P,Q and R in 1 hour = 1/8 + 1/10 + 1/12 = 37/120****Work done by Q and R in 1 hour = 1/10 + 1/12 = 22/120 = 11/60****From 9 am to 11 am, all the machines were operating.****Ie, they all operated for 2 hours and work completed = 2 × (37/120) = 37/60****Pending work = 1- 37/60 = 23/60****Hours taken by Q an R to complete the pending work = (23/60) / (11/60) = 23/11****which is approximately equal to 2****Hence the work will be completed approximately 2 hours after 11 am ; ie around 1 pm**