Package Delivery by Drones. Amazon.com is testing the use of drone
delivery times must be sufficiently small. Consider a sample of 24 dro
On the basis of above information, answer the following questions:
Question 1. Construct a 90% confidence interval estimate of the pop
Hint:
Step1: Calculate the degrees of freedom and alpha coefficient for 90%
Step 2: Calculate chi-square values for left tail and right tail by either u
1-alpha/2) or
use CHISQ.INV (alpha/2, degrees of freedom) and CHISQ
Step 3: Calculate the confidence interval of variance by multiplying d
Question 2. Construct a 90% confidence interval estimate of the pop
Hint: Take the square root of the confidence limits of the variance
Answer: 1. The confidence interval estimate of the population variance is 0.52
First find the degrees of freedom, alpha and alpha/2 which is 23 , 0.1 Then calculate the left tail using =CHISQ.INV(0.05, 23) = 13.09051 an
23) = 35.17246 To find the confidence interval lower limit ( 23 * 0.81) / 35.17246 = 0.
* 0.81) / 13.09051 = 1.423168 2. The confidence interval estimate of the population standard deviati
To get these values, square root the values of the confidence interval