Question

the mean annual income for people in a certain city is 46 (thousands of dollars), with a standard deviation of 42. A pollster draws a sample of 60 people to interview. What is the probability that the sample mean income is less than 42 (thousands of dollars)?

Answer 1

Solution :

Given that ,

mean = = 46

standard deviation = = 42

= / n = 42 / 60

P( < 42) = P(( - ) / < (42 - 46) / 42 / 60)

= P(z < -0.74)

= 0.2297