Pacing The Distance

A fellow was walking along a country road and came upon a farmer working
in his field. The man called out to the farmer and asked how long it
would take him to get to the next town.

The farmer didn't answer. So, after waiting a bit, the fellow started
walking again.

After the man had gone about 100 paces, the farmer yelled to him and
said, "About 20 minutes."

Confused, the man turned back toward the farmer and inquired, "Why
didn't you tell me that when I asked you?"

The farmer replied, "I needed to see how fast you walk first."