Solution:

He was walking

Solution:

Dozens

Solution:

There is no smoke with an electric train.

Solution:

SQRT(.2 ^ -2)

Take .2 and raise it to the power of -2 and then take the square root.

Solution:

Each word has 3 consecutive letters of the alphabet-
couGHIng (GHI)
thiRSTy (RST)
DEFiant (DEF)

Solution:

The wife was about to have a baby. They were driving to the hospital. The baby was born, and the wife didn't survive the birth

Solution:

The mathematician made a small fence around himself and declared himself to be on the outside.

Solution:

Only twenty-three people need be in the room, a surprisingly small number. The probability that there will not be two matching birthdays is then, ignoring leap years, 365x364x363x...x343/365 over 23 which is approximately 0.493. this is less than half, and therefore the probability that a pair occurs is greater than 50-50. With as few as fourteen people in the room the chances are better than 50-50 that a pair will have birthdays on the same day or on consecutive days.

Solution:

1:45

The man gave away a total of 25 cents. He divided it between two people. Therefore, he gave a quarter to two

Solution:

On a sailboat (sale boat).