1(a)How many different sequences of heads and tails are possible if a coin is flipped 100 times? Using the fact that 2¹⁰=1024 is approximately equal 1000=10³ ,give your answer in terms of an(approximate)power of 10.

(b)How many four-letter "words" (sequence of any four letters with repetition)are there? How many with no repeated letters?

(c)How many ways are there to pick a man and a woman who are not husband and wife from a group of n married couples?