Question

in 1990, the mean amount of time car owners kept their cars was 6.3 yrs and the standard deviation of these times was 3 yrs. thinking this mean ownership time may have changed (in either direction) over the past decade, a poll of 100 randomly selected car owners was conducted, revealing that the sample mean length of time they plan to keep their cars is 6.99 yrs. we will assume the standard deviation of all times is still 3 years.
A) what is the population?

B) what ist he variable of interest?
C) what are the appropriate null and alternative hypotheses?
D) determine the value of the appropriate observed test statistic to perform this test.
E)determine the value of the p-value for this test.

F) statistival conlusition: Accept or Reject, Why?

Answer 1