Question

2. Data was collected from a highway with a 65 mph speed limit. A speed “gun” sampled 12 random vehicles and found the mean to be 60.67 mph with a standard deviation of 4.08 mph. i. Which model would be used to construct a confidence interval for the mean 2i) speed of all vehicles on that highway? a) students-t b) least squares linear regression c) Binomial d) Normal ii. The standard deviation for this sampling distribution would be calculated using, 2ii) a) s b) c) ∑ d) iii. The 90% confidence interval from this sample is (58.55, 62.79). This means 2iii) that we are 90% confident that, a) 58.55% to 62.79% of all vehicles were driving under the speed limit b) 58.55% to 62.79% of the sample vehicles were driving under the speed limit. c) The mean speed of the sample vehicles is between 58.55mph and 62.79mph. d) The mean speed of all vehicles is between 58.55mph and 62.79mph

Answer 1

sample Mean = 60.67

by sing t critical
t critical = 1.8
sM = √(4.082/12) = 1.18
μ = M ± t(sM)
μ = 60.67 ± 1.8*1.18
μ = 60.67 ± 2.12

90% CI [58.55, 62.79].

You can be 90% confident that the population mean (μ) falls between 58.55mph and 62.79 mph OPTION D