assume that when adults with smartphones are randomly selected 52% use them in meetings or classes. if 12 adult smartphone users are randomly selected find the probability that fewer than 4 of them use their smartphones in meetings or classes?

0.056

Step-by-step explanation:

Use binomial probability:

P = nCr pʳ qⁿ⁻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).

P(r<4) = P(0) + P(1) + P(2) + P(3)

P(r<4) = ₁₂C₀ (0.52)⁰ (0.48)¹²⁻⁰ + ₁₂C₁ (0.52)¹ (0.48)¹²⁻¹ + ₁₂C₂ (0.52)² (0.48)¹²⁻² + ₁₂C₃ (0.52)³ (0.48)¹²⁻³

P(r<4) = (0.48)¹² + 12 (0.52) (0.48)¹¹ + 66 (0.52)² (0.48)¹⁰ + 220 (0.52)³ (0.48)⁹

P(r<4) = 0.056