Question

The number of booker borrowed from a library each week follows a normal distribution. When sample is taken for several weeks, the mean is found to be 190 and the standard deviation is 30

Answer 1

2.5%

Explanation:

Given :

Mean, μ = 190

Standard deviation, σ = 30

Probability that more than 250 books are borrowed ;

x = 250

P(Z > z)

Z = (x - μ) / σ

P[Z > (x - μ) / σ] = P[Z > (250 - 190) / 30]

P(Z > z) = P(Z > 2)

P(Z > 2) = 1 - P(Z < 2) = 1 - 0.97725

P(Z > 2) = 1 - P(Z < 2) = 0.02275

(0.02275 * 100)% = 2.275%

2.5% is closest to 2.275%