Question

The BigBux corporation wants to know how the population feels about their latest product, SmartAir. If the score is at least 3 out of 5 stars they’ll release the product. Unknown to them, the population mean score of SmartIce is µ = 2.4 stars with a standard deviation of σ = 1.2 stars. BigBux takes a sample of 36 randomly-chosen individuals and tests the product on them. What is the probability that the sample mean score these people give SmartAir is over 3 stars?

Answer 1

Solution :

Given that ,

= 2.4

= / n = 1.2 / 36 = 0.2

P( > 3) = 1 - P( < 3)

= 1 - P[( - ) / < (3 - 2.4) / 0.2 ]

= 1 - P(z < 3.0)   

= 1 - 0.9987

= 0.0013