I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

A large water tank has two inlet pipes (a large one and a small one) and one outlet pipe. It takes 3 hours to fill the tank with the large inlet pipe. On the other hand, it takes 6 hours to fill the tank with the small inlet pipe. The outlet pipe allows the full tank to be emptied in 9 hours.

What fraction of the tank (initially empty) will be filled in 0.64 hours if all three pipes are in operation? Give your answer to two decimal places (e.g., 0.25, 0.5, or 0.75).

A landlord calls both of his sons and tells them that their horses will now decide who will transfer the inheritance. He tells them to race along the land till the end and the one whose horse will be slower will win and be the heir to all the property.

Both of them keep wandering for days but to no result. Then they ask a wise man regarding it. The man advises them on the matter after which they jump on the horses and race as fast as they can till the end. Why did they do it?

What did the wise man say?

You have two buckets of 11 liters and 6 litres.
How can you measure exactly 8 litres?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

Rectify the following equality 101 - 102 = 1 by moving just one digit.

On a bright sunny day, two fathers took their son fishing in the lake. Each man and son were able to catch one fish. When they returned to their camp, there were only three fishes in the basket. What happened?

PS: None of the fish were eaten, lost, or thrown back.

What time is it when an elephant sits on a fence?

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?