a Assume that a word consists of 7 lowercase letters of the

a. Assume that a word consists of 7 lower-case letters of the alphabet. Assume that repeated letters are NOT allowed to use in the word. How many words begin with “t”?

b) Assume that a word consists of 7 lower-case letters of the alphabet. Assume that repeated letters are allowed to use in a word. How many words begin with “b”?

Solution

a)

1 * 7 * 6 * 5 *4 * 3 *2 = 5040

b)

1*7*7*7*7*7*7 = 117649