Question

The selling price of a calculator offered by businesses in the metropolitan area is a variable obeying a normal law of average $ 19.65 with a standard deviation of $ 1.16. If we take a sample of 10 businesses in the metropolitan area offering this calculator, what is the probability that the average selling price is more than $ 20?

Answer 1

Solution :

= / n = 1.16 / 10 = 0.3668

P( > $20) = 1 - P( < 20)

= 1 - P[( - ) / < (20 - 19.65) / 0.3668]

= 1 - P(z < 0.95)

= 1 - 0.8289

= 0.1711

Probability = 0.1711