A coin for which the probability of heads is 06 is tossed ni

A coin for which the probability of heads is 0.6 is tossed nine times. Find the probability of obtaining an even number of heads.

Solution

probability of getting heads = p = 0.6

that of getting tails = 1-p = 0.4

it is tossed nine times , inorder to get even heads the options are

2 heads , 4 heads , 6 heads , 8 heads

2 heads : 9!/(2! . 7!) = 36 * (0.6)^2 * ( 0.4)^7

4 heads : 9!/(4! . 5!) = 126 *(0.6)^4 * (0.4)^5

6 heads : 9!/(6! . 3!) = 84 * (0.6)^6 * (0.4)^3

8 heads : 9!/(8! . 1!) = 9 * (0.6)^8 * (0.4)

probability = adding everything = 0.4997