## Thursday, November 26, 2015

### Concept of Mandays, Pipes and Cisterns, Time and Work Special Case with solved examples Video

This is the second video of Time and Work module. In this video I have started with the concept of mandays. Specific types of questions concept which involve the comparison of work and efficiency have been explained by me and an easy method of solving them has been detailed. Then I have taken up the explanation of Pipes and Cisterns topic. In many books and coaching institutes the topic of Time Work and Pipes Cisterns is dealt with separately but according to me both of them are basically the same thing and there is a need to study them in totality as in the questions of Pipes Cisterns, the total work is filling or emptying of the cistern or tank. After that I have taken a special type of question which we very often see in Time and Work questions. I have told the shortcut for attempting it directly. On all these concepts, I have explained below questions which would help you understand the practical applications of all these concepts.

Question 1. If 3 boys or 4 girls can construct a tower in 43 days, then in how many days will 7 boys and 5 girls together take to construct it ??

Question 2. In 16 days, 45 persons can complete a particular job. After working on the job for 6 days, 30 more persons joined the rest. In how many days from now would they complete the job ??

Question 3. Five men take as much time to do a job as 10 women take. If 6 men take 10 days to complete a job working 4 hours a day, how much time would 10 women take to do a job twice as much as the former working 6 hours in a day ??

Question 4. A man, a woman and a boy can finish a job in 3 days, 4 days and 12 days respectively. How many boys must assist 1 man and 1 woman to do the job in 1.5 days ??

Question 5. If 3 men and 2 women together earn Rs. 306 in 9 days while 7 men and 3 women earn Rs. 639 in the same time. In how many days will 8 men and 6 women together earn Rs. 376 ??

Question 6. Because of a leak, the tank which is usually filled in 3 hours, now takes 3.5 hours to get filled. The leak alone will empty the full tank in

Question 7. Two pipes P1 and P2 can fill a tank in 36 minutes and 45 minutes respectively. A third pipe P3 can empty the tank in 30 minutes. Initially both P1 and P2 are opened. After 7 minutes, P3 is also opened. In how much time from the beginning the tank will be full ??

Question 8. Two pipes P1 and P2 can fill a tank in 12 minutes and 15 minutes respectively. A third pipe P3 empties the full tank in 6 minutes. P1 and P2 are kept open for five minutes initially and then pipe P3 is also opened. Find out whether the tank will get filled or emptied after that and in how many minutes after the first five minutes ??

Question 9. Two pipes can fill a cistern in 14 hours and 16 hours respectively. Two pipes are opened simultaneously and it is found that due to leakage in the bottom of the cistern, it takes 32 minutes for the cistern to be filled up. When the cistern is full and only the leakage is operating in what time the leak would empty it ??

Question 10. A tank T can be filled by an inlet pipe of circular cross section in 10 minutes. Another tank twice as big is filled in by 3 inlet pipes whose diameters are in the ratio 1:2:3 . If the smallest pipe among these is four times as much in cross section as the inlet pipe of tank T. Find the time taken to fill the second tank if the speed of water flowing into the second tank is half the speed of water flowing into tank T.

Question 11. The time taken by A and B individually to complete a work is 4 hours and 9 hours more respectively than the time taken by both of them combinedly to complete the same work. Find the time taken by B to complete the work all on his own ??

Question 12. Anil can stitch a suit in 3 hours less than Sunil. Anil stitches it alone for 4 hours and then Sunil takes over and completed the stitching. If altogether 14 hours were taken to stitch the suit, how many hours Sunil and Anil individually would take to stitch the suit ??

Question 13. X alone would take 8 hours more to complete a job than both X and Y together. If Y worked alone, he took 4.5 hours more to complete it than both X and Y together. What time would they take if both X and Y worked together ??