Scope of Inference — Quiz

Question 9 • Statistics

Using the dotplot and the sample mean mileage, is there convincing evidence that the new type of tread improves the mileage?

Answer

Yes, because a mean mileage of 52,000 or more occurred only 7 out of 200 times, the mean mileage is statistically significant. There is convincing evidence the new type of tire tread improves mileage of the tire.

No, because a mean mileage of 52,000 or less occurred 193 out of 200 times, the mean mileage is not statistically significant. There is not convincing evidence the new type of tire tread improves mileage of the tire.

Yes, because a mean mileage of 52,000 or less occurred 193 out of 200 times, the mean mileage is statistically significant. There is convincing evidence the new type of tire tread improves mileage of the tire.

No, because a mean mileage of 52,000 or more occurred 7 out of 200 times, the mean mileage is not statistically significant. There is not convincing evidence the new type of tire tread improves mileage of the tire.

Explanation

If only 7 of the 200 simulated mean mileages were 52,000 or more, that is a small proportion (7/200 = 0.035, or 3.5%). Such a result would be unusual if the new tread did not improve mileage, so the sample mean provides statistically significant evidence of improvement. The correct choice is C: only 7 out of 200 mean mileages were 52,000 or more, supporting the claim that the tread improves mileage.

AI-written and checked against the verified answer.

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