#### Answer

Answer: $a.$ Less than 25 hours

#### Work Step by Step

The reason is very simple:
If the second pipe can $alone$ fill the pond in 25 hours, any help from the first pipe will reduce the total time the pond is filled in.

Published by
Pearson

ISBN 10:
0321726391

ISBN 13:
978-0-32172-639-1

Answer: $a.$ Less than 25 hours

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