Question

2. In a study of stereotypes on infants, 77% of female babies choose a baby doll over a football. If 18 female babies are chosen at random, find the probability that exactly 10 of them will choose a baby doll over a football.

Answer 1

Solution

Given,

p = 77% = 0.77 success probability

n = 18 number of trials

So, X follows Binomial(n = 18 , p = 0.77)

Find P(Exactly 10) i.e P(X = 10)

Using binomial probability formula ,

P(X = x) = (_n C _x) * p^x * (1 - p)^{n - x}

P(X = 10) = (₁₈C ₁₀) * 0.77¹⁰ * (1 - 0.77)^{18 - 10}

=  0.02510657111

Probability = 0.02510657111