How long will it take for the leak to drain the full cistern? I. Normally, the cistern is full in 9 hours. II. Due to a leak in the bottom, it takes an hour longer to fill the cistern than usual.
A. I alone sufficient while II alone not sufficient to answer
B. II alone sufficient while I alone not sufficient to answer
C. Either I or II alone sufficient to answer
D. Both I and II are necessary to answer
Answer:D
How long will it take for the leak to drain the full cistern? I. Normally, the cistern is full in 9 hours. II. Due to a leak in the bottom, it takes an hour longer to fill the cistern than usual.
A. I alone sufficient while II alone not sufficient to answer B. II alone sufficient while I alone not sufficient to answer C. Either I or II alone sufficient to answer D. Both I and II are necessary to answer
Explanation: I. Filling the cistern without a leak took 9 hours.In 1 hour, a portion of the cistern was filled without leaking = 1/9.II. Filling the cistern in the presence of a leak takes 10 hours.1/10 net filling in 1 hourLeak's work in an hour = 1/9 - 1/10 = 1/90.The full cistern will be emptied in 90 hours due to the leak.