Use the following information for questions:
A safety officer wants to prove that $\mu$ = the average speed of cars driven by a school is less than 25 mph. Suppose that a random sample of 14 cars shows an average speed of 24.0 mph, with a sample standard deviation of 2.2 mph. Assume that the speeds of cars are normally distributed.
-Which of the following is an appropriate conclusion?
A) The results are statistically significant so the average speed appears to be greater than 25 mph.
B) The results are statistically significant so the average speed appears to be less than 25 mph.
C) The results are not statistically significant: there is not enough evidence to conclude the average speed is less than 25 mph.
D) None of the above.

Question

Use the following information for questions:
 A safety officer wants to prove that $\mu$ = the average speed of cars driven by a school is less than 25 mph. Suppose that a random sample of 14 cars shows an average speed of 24.0 mph, with a sample standard deviation of 2.2 mph. Assume that the speeds of cars are normally distributed.
-Which of the following is an appropriate conclusion?
A) The results are statistically significant so the average speed appears to be greater than 25 mph.
B) The results are statistically significant so the average speed appears to be less than 25 mph.
C) The results are not statistically significant: there is not enough evidence to conclude the average speed is less than 25 mph.
D) None of the above.

Quizplus · Accepted Answer

The sample mean is 24.0 mph, which is less than 25 mph, but the sample size is small (n=14). A t-test would be used to determine if the difference is statistically significant. Without the test statistic or p-value, we cannot conclude that the average speed is significantly less than 25 mph.

Use the Following Information for Questions: a Safety Officer μ\muμ

Use the Following Information for Questions:
a Safety Officer $\mu$