Question

A coin is tossed 7 times. What is the probability of getting all tails? Express your answer as a simplified fraction or a decimal rounded to four decimal places.

Answer 1

0.0078125

Explanation:

Probability of tail, p = 0. 5

Probability of getting all tails from 7 tosses :

P(tail) * P(tail) * P(tail) * P(tail) * P(tail) * P(tail) * P(tail)

0.5 * 0.5 * 0.5 * 0.5 * 0.5 * 0.5 * 0.5 = 0.0078125

We could also use the binomial probability formula :

P(x =x) = nCx * p^x * (1 - p)^(n - r)

n = 7 ; x = 7, p = 0.5,

P(x = 7) = 7C7 * 0.5^7 * 0.5^0 = 0.0078125