In: Statistics and Probability
The mean salary of people living in a certain city is $37,500 with a standard deviation of $2,348. A sample of 62 people is selected at random from those living in the city.
Find the probability that the mean income of the sample is within $500 of the population mean.
Round your answer to 4 decimal places.
Solution :
Given that,
mean = = 37500
standard deviation = = 2348
n = 62
= = 37500
= / n = 2348 / 62 = 298.20
37500 ± 500 = 37000, 38000
P(37000 < < 38000)
= P[(37000 - 37500) / 298.20 < ( - ) / < (38000 - 37500) / 298.20 )]
= P(-1.68 < Z < 1.68)
= P(Z < 1.68) - P(Z < -1.68)
Using z table,
= 0.9535 - 0.0465
= 0.9070