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

Question

Mathematics

Kevin Joyce

29 June, 18:07

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

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Answers (1)

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Alana Blevins · Answer 1

Solution:

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