Exercise 11
Question 1
1. 6 men can complete the electric fitting in a building in 7 days. How many days will it take 21 men to do the job?
2. Shashi weaves 25 baskets in 35 days. In how many days will she weave 110 baskets ?
3. Two men can do a piece of work in 3 days and 6 days respectively. If they work together, in how many days will they finish the work?
4. One man can do a piece of work in 3 hours ; another can do the same piece of work in 2 hours. How long will they take if they work together?
5. $A$ and $B$ together can do a piece of work in 10 days, but $A$ alone can do it in 15 days. How many days would $B$ alone take to do the same work ?
6. Two men can do a piece of work in 6 hours and 4 hours respectively. After the first has worked for 2 hours, he is joined by the other. By when should the work be completed ?
7. $A, B$ and $C$ can cultivate a field in 10,12 , and 15 days respectively. If they work together, in how many days will they finish the work and what fraction of the work will each of them do ?
8. $A, B$ and $C$ can do a piece of work in 10 days. $A$ alone can do it in 40 days, and $B$ alone can do it in 30 days. In how many days will $C$ alone do the same work?
9. $A$ and $B$ can do a given piece of work in 8 days; $B$ and $C$ can do the same work in 12 days and $A, B, C$ complete it in 6 days. In how many days can $A$ and $C$ finish it?
10. A cistern can be filled by one tap in 4 hours and by another in 3 hours. How long will it take to fill if both taps are opened together?
11. A cistern can be filled by a tap in 4 hours and emptied by an outlet pipe in 6 hours. How long will it take to fill the cistern if both taps are opened together?
12. One tap fills a bath in $12 \mathrm{~min}$. and another tap fills it in $15 \mathrm{~min}$. The waste-pipe can empty the bath in $10 \mathrm{~min}$. In what time will the bath be filled if both taps are turned on and if the waste-pipe has been left open accidentally ?
13. A pipe can fill a cistern in 6 hours. Due to a leak in the bottom it is filled in 7 hours. When the cistern is full, in how much time will it be emptied by the leak ?
14. A cistern has two inlets $A$ and $B$ which can fill it in 15 hours and 20 hours respectively. An outlet car empty the full cistern in 12 hours. If all the three pipes are opened together in the empty cistern, how much time will they take to fill the cistern completely?
Multiple Choice Questions (MCQs)
15. $A$ and $B$ together take 5 days to do a work, $B$ and $C$ take 7 days to do the same and $A$ and $C$ take 4 days to do it. Who among these will take the least time, if put to do it alone?
(a) $A$
(b) $B$
(c) $C$
(d) data is not adequate
16. A tap can empty a tank in one hour. A second tap can empty it in 30 minutes. If both the taps operate simultaneously, how much time is needed to empty the tank?
(a) 20 min.
(b) 30 min.
(c) 40 min.
(d) 45 min.
High Order Thinking Skills (HOTS)
17. $A$ and $B$ can finish a work in 30 days. They worked for it for 20 days and then $B$ left. The remaining work was done by $A$ alone in 20 more days. $A$ alone can finish the work in
(a) 54 days
(b) 60 days
(c) 48 days
(d) 50 days
18. Pipes A and B can fill a tank in 5 and 6 hours respectively. Pipe C can empty it in 12 hours. The tank is half full. All the three pipes are in operation simultaneously. After how much time will the tank will be full.
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