Question

Researcher Seth B Young measured the walking speed of travelers in San Francisco International Airport and Cleveland Hopkins International Airport. The standard deviation speed of 35 travelers who were departing was 53 feet per minute. The standard deviation speed of 35 travelers who were arriving was 34 feet per minute. Assume the walking speed is normally distributed. a) Test whether the standard deviation walking speed is different for the two groups at 1% level of significance. b) Calculate a 99% Confidence Interval for the standard deviation difference between the two groups.

Answer 1

To Test :-

H0 :-  

H1 :-  

Test Statistic :-

f = 2809 / 1156
f = 2.4299

Test Criteria :-
Reject null hypothesis if


2.4299 lies between the value 2.471 and 0.41 , hence we fail to reject the null hypothesis
Conclusion :- We Fail to Reject H0

Decision based on P value
P value = 2 * P ( f > 2.4299 )
P value = 0.0114
Reject null hypothesis if P value <
Since P value = 0.0114 > 0.01, hence we fail to reject the null hypothesis
Conclusion :- We Fail to Reject H0

There is insufficient evidence to support the claim that the standard deviation walking speed is different for the two groups at 1% level of significance.

Part b)

n1 = 35
n2 = 35




Lower Limit =
Upper Limit =
99% Confidence interval is ( 0.9838 , 6.0019 )
( 0.9838 < < 6.0019 )

( 0.9919 <    < 2.4499 )