An air travel service samples domestic airline flights to explore the relationsh
ID: 2708150 • Letter: A
Question
An air travel service samples domestic airline flights to explore the relationship between airfare and distance. The service would like to know if there is a correlation between airfare and flight distance. If there is a correlation, what percentage of the variation in airfare is accounted for by distance? How much does each additional mile add to the fare? The data follow.
Compute the correlation of distance and fare? (Round your answer to 3 decimal places.)
State the decision rule for 0.05 significance level: H0: r %u2264 0; H1: r > 0. (Round your answer to 2 decimal places.)
Compute the value of the test statistic. (Round your answer to 2 decimal places.)
At the 0.05 significance level, is it reasonable to conclude that the correlation coefficient is greater than zero?
What percentage of the variation in Fare is accounted for by Distance of a flight? (Round your answer to the nearest whole number.)
Determine the regression equation. (Round your answers to 5 decimal places.)
How much does each additional mile add to the fare? (Round your answer to 5 decimal places.)
Estimate the fare for a 2,000-mile flight. (Round your answer to 2 decimal places.)
Explanation / Answer
(b-1) r=0.208
(b-2) Given a=0.05, the critical value is t(0.95, df=n-2=28) =1.701
Reject H0 if t >1.701
(b-3)test statistic
= r*sqrt((n-2)/(1-r^2))
=0.208*sqrt(28/(1-0.208^2))
=1.13
(b-4) Do not reject Ho. There is not enough evidence to conclude that a positve correlation exists.
(c) R^2= 4.34%
(d-1)
regression equation:
y=193.1705+0.0203*Distance
(d-2)No. of additional miles: 0.0203
(d-3)
y=193.1705+0.0203*1250=218.5455
confidence interval variables coefficients std. error t (df=28) p-value 95% lower 95% upper Intercept 193.1705 24.9183 7.752 1.91E-08 142.1277 244.2134 Distance 0.0203 0.0180 1.128 .2691 -0.0166 0.0572
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