The following output was obtained using information recorded on 80 vehicles which had been involved in serious motor vehicle accidents. You may assume that both the ages of the vehicles (Age) are normally distributed.

Assuming the ages of vehicles in accidents are known to have a standard deviation of 3.5 years, use the following tables to calculate a 95% confidence interval to estimate the mean age of vehicles involved in serious road accidents.

VariableNMeanStDevMinimumMaximum

Age818.0452.7352.10015.393

Select one:

a.(7.449, 8.650)

b.(7.283, 8.807)

c.(7.405, 8.685)

d.(7.440, 8.650)

e.none of these options