12. | A large tanker can be filled by two pipes A and B in 60 minutes and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if B is used for half the time and A and B fill it together for the other half? | |||||||||||||||||||||||||||||||||||||
Answer: Option D Explanation:
Suppose the tank is filled in x minutes.
x = 30 min. |
13. | A tap can fill a tank in 6 hours. After half the tank is filled, three more similar taps are opened. What is the total time taken to fill the tank completely? | ||||||||||||||||||||||||||||||||||||||||||||||
Answer: Option B Explanation:
Time taken by one tap to fill half of the tank = 3 hrs.
So, total time taken = 3 hrs. 45 mins. |
14. | Three taps A, B and C can fill a tank in 12, 15 and 20 hours respectively. If A is open all the time and B and C are open for one hour each alternately, the tank will be full in: | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Answer: Option C Explanation:
Total time taken to fill the tank = (6 + 1) hrs = 7 hrs. |
15. | Three pipes A, B and C can fill a tank in 6 hours. After working at it together for 2 hours, C is closed and A and B can fill the remaining part in 7 hours. The number of hours taken by C alone to fill the tank is: | ||||||||||||||||||||||||||||||||||||||||
Answer: Option C Explanation:
C’s 1 hour’s work = { (A + B + C)’s 1 hour’s work } – { (A + B)’s 1 hour’s work }
C alone can fill the tank in 14 hours |