One pump drains one-half of a pond in 5 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?
Answers:	A) 1 hour	B) 1.2 hour	C) 3 hours	D) 5 hours	E) 1.1 hours
The tricky part here, I believed is one half hour = 1/2. Then everything would be easy.   We have the 1st pump working rate/hour = 1/2 : 5 = 1/10   Working rate of 2 pumps: 1/2 : 1/2 = 1.   Working rate of 2nd pump: 1 -1/10 = 9/10 --&gt; Time taken for the 2nd pump to finish: 1 : 9/10 = 10/9 = 1.1 hours.   1.1 hours
<result>E</result>
One pump drains one-half of a pond in 5 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?