Answer: The test statistic ? is 3.17.
Explanation:
To conduct a hypothesis testing to see if the population mean speed on the off-ramp is 45 mph at a 95% confidence level, we need to set up the null and alternative hypotheses:
Null hypothesis: The population mean speed on the off-ramp is 45 mph (μ = 45)
Alternative hypothesis: The population mean speed on the off-ramp is not 45 mph (μ ≠ 45)
We can use a two-tailed t-test since we do not have any prior knowledge about the direction of the difference.
Next, we need to calculate the test statistic:
t = (sample mean - hypothesized population mean) / (sample standard deviation / sqrt(sample size))
t = (46.5 - 45) / (4.1 / sqrt(60))
t = 3.17
The degrees of freedom (df) for this test is (n - 1) = 59. We can find the critical value using a t-table or a t-distribution calculator for a 95% confidence level with df = 59:
t_critical = ±2.002
Since our calculated t-value (3.17) is outside the range of the critical values (-2.002, 2.002), we can reject the null hypothesis and conclude that there is sufficient evidence to suggest that the population mean speed on the off-ramp is not 45 mph at a 95% confidence level.
Answer: The test statistic ? is 3.17.