Question

Assume that when adults with smartphones are randomly​ selected, 42​% use them in meetings or classes. If 30 adult smartphone users are randomly​ selected, find the probability that exactly 24 of them use their smartphones in meetings or classes.

Answer 1

0.00205%

Explanation:

Use binomial probability:

P = nCr p^r q^(n-r)

where n is the number of trials,

r is the number of successes,

p is the probability of success,

and q is the probability of failure (1-p).

n = 30, r = 24, p = 0.42, and q = 0.58.

P = ₃₀C₂₄ (0.42)²⁴ (0.58)³⁰⁻²⁴

P ≈ 0.00205%