In: Statistics and Probability
In a sample of 36 suitcases , the avg is 45 lbs. Standard deviation is 8.2. Construct at 90% confidence interval for the mean of the weight of all suticases
Solution :
Given that,
= 45
= 8.2
n = 36
At 90% confidence level the z is ,
= 1 - 90% = 1 - 0.90 = 0.10
/ 2 = 0.10 / 2 = 0.05
Z/2 = Z0.05 = 1.645
Margin of error = E = Z/2* ( /n)
=1.645 * (8.2 / 36)
= 2.2482
At 90% confidence interval estimate of the population mean is,
- E < < + E
45 - 2.2482 < < 45 + 2.2482
42.7518 < < 47.2482
(42.7518 , 47.2482)