In: Math
graduate student wants to estimate the number of research participants he will see in the fall semester. Using his data from the previous nine semesters, he tabulates a mean of 140 students per semester, although departmental records reflect a seasonal variation (i.e., population standard deviation) of 45 students. Calculate the 99% confidence interval.
Solution :
Given that,
= 140
= 45
n = 9
At 99% confidence level the z is ,
= 1 - 99% = 1 - 0.99 = 0.01
/ 2 = 0.01 / 2 = 0.005
Z/2 = Z0.005 = 2.576
Margin of error = E = Z/2* ( /n)
= 2.576 * (45 / 9)
= 38.64
At 99% confidence interval estimate of the population mean is,
- E < < + E
140 - 38.64 < < 140 + 38.64
101.36 < < 178.64
(101.36 , 178.64)