3)Records of 40 used passenger cars and 40 used pickup trucks (none used commercially) were randomly selected to investigate whether there was any difference in the mean time in years that they were kept by their original owners before being sold.For sample of cars, the mean was 5.3 years with standard deviation 2.2years and for the pickup trucks, the mean was 7.1 years with s = 3.0years.

a)State whether the sample independent or dependent? Justify.

b)Construct and interpret the 95% confidence interval for the difference in the mean time that they were kept by their original owners.

c)Based on this interval can you conclude that that there is a difference in the mean time that car and pickup trucks were kept by their original owners? Justify. What do the signs in the interval indicate?