In: Statistics and Probability
The mean per capita income is 23,334 dollars per annum with a standard deviation of 666 dollars per annum. What is the probability that the sample mean would be less than 23182 dollars if a sample of 168 persons is randomly selected? Round your answer to four decimal places.
SOLUTION:
From given data,
The mean per capita income is 23,334 dollars per annum with a standard deviation of 666 dollars per annum. What is the probability that the sample mean would be less than 23182 dollars if a sample of 168 persons is randomly selected
The mean per capita income = = 23334
standard deviation = = 666
the sample mean= = 23182
sample = n = 168
The Z score for = 23182 is
Z = ( - ) / ( / )
= ( 23182 - 23334 ) / (666 / )
= -152 / 51.383015
Z = - 2.95
The required probability is
P( < 23182 ) = P( z < - 2.95 )
= 0 .00159
0.0016
Excel function used to find the probability is: = "=NORMSDIST(- 2.95)"