Question

What is the probability that at least 70 use their phone at least once per hour?

Answer 1

P(x₁ ≥ 70)

Z= (x-µ)/σ

µ = np

σ = √np(1-p)

P(x₁ ≥ 70) = p(x₁-np₁/√np₁ (1-p₁) > 70 – (150*0.51)/√150*0.51*0.49)

= p( z₁ ≥ -1.1433)

= 1-p (z₁ ≤ -1.1433)

= 1- 0.1265

= 0.8735