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Samples of two different models of cars were selected, and the actual speed for each car was determined when the speedometer registered \(50 \mathrm{mph}\). The resulting \(95 \%\) confidence intervals for mean actual speed were \((51.3,52.7)\) and \((49.4,50.6)\). Assuming that the two sample standard deviations are equal, which confidence interval is based on the larger sample size? Explain your reasoning.

Short Answer

Expert verified
The confidence interval with the larger sample size is \( (49.4, 50.6) \). This is because its width is smaller than the other given confidence interval, suggesting a larger sample size given equal standard deviations.

Step by step solution

01

Identify Confidence Intervals

Identify the two sets of confidence intervals, which are: \( (51.3, 52.7) \) and \( (49.4, 50.6) \).
02

Calculate the Width of Confidence Intervals

Calculate the width of each confidence interval by subtracting the lower limit from the upper limit. For the first confidence interval, the width is \( 52.7 - 51.3 = 1.4 \). And for the second, it is \( 50.6 - 49.4 = 1.2 \).
03

Compare the Widths

Compare the widths of these confidence intervals. Because the confidence interval will be narrower with larger sample size, given constant standard deviation, the narrower interval suggests a larger sample size.

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