Question

In how many ways can clean & clouded (overcast) days occur in a week assuming that an entire day is either clean or clouded.

Answer 1

Each day has 2 possibility either clear or clouded.

Hence, Permutation of a week:

$=2\cdot 2\cdot 2\cdot 2\cdot 2\cdot 2\cdot 2=2^7=128$