6. A study was conducted to determine whether the mean braking distance of four-cylinder cars is greater than the mean braking distance of six-cylinder cars. A random sample of 20 four-cylinder cars and a random sample of 20 six-cylinder cars were obtained, and the braking distances were measured.

(a) What would be the appropriate hypothesis test for this analysis?

(i)t-test for two independent samples

(ii)t-test for dependent samples

(iii)z-test for population mean

(iv)correlation

(b) Explain the rationale for your selection in (a). Specifically, why would this be the appropriate statistical approach?