Question

Suppose students are independent from one another. 63% of students are using Mr. Martin's new social media app, Mar-tin-stagram. 2 students are randomly selected. What is the probability that both of them use it? (Write answer as a decimal. Do not round)

Answer 1

`P(X=2) =0.3906`

Explanation:

Proportion of students using the app, p = 63/100 = 0.63

Proportion of students not using the app, q = 1 - 0.63 = 0.37

Sample size, n = 2

Probability that the two students are using the app.

`P(X = r) = nCr p^(n) q^(n-r) \\P(X = 2) = 2C2 *0.63^(2) *0.37^(2-2)\\P(X = 2) = 2C2 *0.63^(2) *0.37^(0)\\P(X=2) = 0.63^(2) \\P(X=2) =0.3906`