Subject: mathqa
Question: one pump drains one - half of a pond in 7 hours , and then a second pump starts draining the pond . the two pumps working together finish emptying the pond in one - half hour . how long would it take the second pump to drain the pond if it had to do the job alone ?
Option: 
A: 3 hours
B: 1 hour
C: 6 hours
D: 1.1 hour
Answer: D