Question

Eunice Gunterwal is a frugal undergraduate at State U. who is interested in purchasing a used car. She randomly selected a sample of 12 want ads in the city where she lives and found that the car prices (in $) were: 3250, 3500, 3100, 3750, 2975, 3800, 2950, 3600, 3550, 4000, 4250, 4800. Determine the 95% confidence interval for the mean price (µ) of used cars in the city.

Answer 1

We have for given data,      
Sample mean =3627.08      
Sample standard deviation =545.59  
Sample size =12      
Level of significance=0.05      
Degree of freedom =11      
              
t critical value is (by using t table)=   2.201      
              
Confidence interval formula is               


=(3280.43,3973.73)