Question 9 Not yet answered Construct the indicated confidence interval for the

Question

Question 9 Not yet answered Construct the indicated confidence interval for the difference between the two population means. Assume that the assumptions and conditions for inference have been met. Marked out of 1.0 The table below gives information concerning the gasoline mileage for random samples of trucks of two different types. P Flag question I I Find a 95% confidence interval for the difference in the means -- by . Brand X Brand Y Number of trucks 50 50 Mean consumption (I100km) 11.25 9.52 Standard Deviation 1.25 0.70 Select one: O a. (1.33, 2.13) a b. (-2.13, -1.33) O C. (0.75, 2.71) Od(3.3, 4.3) O e. (9.52, 11.25)

Explanation / Answer

The 95% confidence interval is been given by :

Mu1-Mu2 +/- Z*sqrt(s1^2/n1 +s2^2/n2)

=11.25-9.52 +/- 1.96*sqrt(1.25^2/50 + .7^2/50) [we know that Z value for 95% CI is 1.96]

= 1.333 to 2.127

or rounding off to 2 digits after decimals:

Confidence interval for 95% confidence is 1.33 to 2.13

a. is right

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