A rental car company claims the mean time to rent a car on their website is 60 s with a standard deviation of 30 s. A random sample 36 customers attempted to rent a car on the website. The mean time...

A rental car company claims the mean time to rent a car on their website is 60 s with a standard deviation of 30 s. A random sample 36 customers attempted to rent a car on the website. The mean time to rent was 75 s. Is this enough evidence to contradict the company’s claim with 95 % confidence?

Testing for significance we use the two-tailed results since we are only interested if the means are different, not if one is larger or smaller than the other.

• The p-value of 0.003 (B11) is smaller than the alpha value of 0.05 (B8). Therefore these results are statistically significant.

• The z-critical value of 1.96 (B12) is less than the z-calculated 3.00 (B7) which also reinforces that these results are statistically significant. Remember when doing this test you need to work with absolute values. We can use these statistically significant results as evidence to contradict the company’s claim with 95 % confidence. The difference in the mean time to ren is real at the 95 % confidence level. Best to change your claim of 60 s to avoid a lawsuit.