Question

1 20.8 1 20.4 1 25.1 1 27.4 1 15.4 1 15.3 1 13.9 2 16.3 2 14.5 2 10.4 2 12.2 2 12.5 2 9.5 2 15.3 3 16.8 3 20.9 3 28.4 3 22.5 3 17.5 3 14.9 3 22.4 3 17.5 3 25.4 3 22.4 4 16.7 4 14.5 4 13.7 4 15.4 4 12.4 4 16 4 7.5 4 12.9 4 18.3  Calculate a 95% confidence interval for the mean mileage of make 2. Use the method for single means when σ is not known, but use the Error Mean Square as the estimate of the variance. The degrees of freedom will be the Error DF, not n 1! Reminders: Confidence Interval = mean ± margin of error Margin of error = critical value * standard error Use critical value for T at /2 = 0.025 and df = error df (t table or EXCEL T.INV function) Use standard error = (error mean square/number of observations of that make of car) 10. What was the margin of error for the confidence interval for gasoline mileage of make 2?

11. What was the lower 95% confidence limit for make 2 mileage?

12. What was the upper 95% confidence limit for make 2 mileage?

 Conduct a test of hypothesis that the mean mileage of makes 2 and 3 do not differ. Use the method for single means when σ is not known with the Error MS serving as the pooled variance. Reminders: Test statistic t = difference of means / standard error of difference of means. The standard error of the difference equals square root of the sum of variances of the two means. The variance of each mean is estimated by the error mean square/number of observations in that mean.

13. What is the value of the t test statistic for testing the hypothesis that makes 2 and 3 do not differ in mileage?

Answer 1

10. What was the margin of error for the confidence interval for gasoline mileage of make 2?

2.3372

11. What was the lower 95% confidence limit for make 2 mileage?

10.62

12. What was the upper 95% confidence limit for make 2 mileage?

15.2943

12.9571	mean Data
2.5271	std. dev.
0.9552	std. error
7	n
6	df
10.6200	confidence interval 95.% lower
15.2943	confidence interval 95.% upper
2.3372	margin of error

13. What is the value of the t test statistic for testing the hypothesis that makes 2 and 3 do not differ in mileage?

t = -4.422

Group 1	Group 2
12.957	20.870	mean
2.527	4.210	std. dev.
7	10	n
	15	df
	-7.9129	difference (Group 1 - Group 2)
	13.1865	pooled variance
	3.6313	pooled std. dev.
	1.7895	standard error of difference
	0	hypothesized difference
	-4.422	t

The data is:

1	2	3	4
20.8	16.3	16.8	16.7
20.4	14.5	20.9	14.5
25.1	10.4	28.4	13.7
27.4	12.2	22.5	15.4
15.4	12.5	17.5	12.4
15.3	9.5	14.9	16
13.9	15.3	22.4	7.5
		17.5	12.9
		25.4	18.3
		22.4