Question

The airlines industry measures fuel efficiency by calculating how many miles one seat can travel, whether occupied or not, on one gallon of jet fuel. The following data show the fuel economy, in miles per seat for 19 randomly selected flights on Delta and United. Assume the two population variance for fuel efficiency for the two airline are equal.

Delta	United
65.80	82.10
81.40	58.80
58.90	60.00
73.60	57.90
72.90	62.80
53.20	45.20
49.80	54.30
68.30	68.40
61.40	52.00
73.10	59.60
67.60	63.10
72.20	67.40
69.40	71.50
61.00	73.30
52.70	77.20
71.40	58.00
44.90	81.10
55.90	88.50
86.70	63.00

     a. Conduct a the 90% confidence interval estimate of the population?

     b. Perform a hypothesis test using α = .05 to determine if the average fuel efficiency differs between the two airlines

     c. Determine the p-value and interpret the results.

Answer 1

a. The 90% confidence interval estimate of the population is between -6.2677 and 6.0571.

b. The hypothesis being tested is:

H0: µ1 = µ2

H1: µ1 ≠ µ2

c. The p-value is 0.9535.

Since the p-value (0.9535) is greater than the significance level (0.05), we fail to reject the null hypothesis.

Therefore, we cannot conclude that the average fuel efficiency differs between the two airlines.

Delta	United
65.274	65.484	mean
10.917	11.197	std. dev.
19	19	n
	36	df
	-0.2105	difference (Delta - United)
	122.2812	pooled variance
	11.0581	pooled std. dev.
	3.5877	standard error of difference
	0	hypothesized difference
	-0.059	t
	.9535	p-value (two-tailed)
	-6.2677	confidence interval 90.% lower
	5.8466	confidence interval 90.% upper
	6.0571	margin of error