Statistical Analysis Subject

The boxplot diagram below shows the price of cars sold privately and by used cars dealers.

No 1.

Z Test for Differences in Two Means
Data
Hypothesized Difference	0
Level of Significance	0.05
Population 1 Sample
Sample Size	89
Sample Mean	15773.61798
Sample Standard Deviation	4840.665989
Population 2 Sample
Sample Size	32
Sample Mean	11741.1875
Sample Standard Deviation	4132.159152
Intermediate Calculations
Difference in Sample Means	4032.430478
Standard Error of the Difference in Means	892.6741
Z Test Statistic	4.5172
Two-Tail Test
Lower Critical Value	-1.9600
Upper Critical Value	1.9600
p-Value	0.00001
Reject the null hypothesis
Upper-Tail Test
Upper Critical Value	1.644853627
p-Value	0.000003
Reject the null hypothesis
Lower-Tail Test
Lower Critical Value	-1.644853627
p-Value	0.999997
Do not reject the null hypothesis

Confidence Interval Estimate
for the Difference Between Two Means
Data
Confidence Level	95.00%
Intermediate Calculations
Z Value	1.9600
Interval Half Width	1749.609066
Confidence Interval
Interval Lower Limit	2282.821411
Interval Upper Limit	5782.0395

From the p-value =0.001>0 = a using the p-value approach, we do not reject the null hypothesis. The difference in price of the car for sale privately and for sale by a used car dealer is different than the probability of getting the difference in our sample is 0.0000000. This is a likely even. Therefore, it is proved that my sample provides actual difference in the average price of the cars of the same make and model in the specified state for sale privately and by a used car dealer.

Age of car is indicated by the price so it is positively influence price of car so I would expect the price to be dependent on the age of the care. So I am constructing a linear model with price as a dependent factor and age as independent factor to enable to predict the price from the age of car.

The scatter diagram below shows the relationship between age and price of used car. As expected this graph shows that the sample the price of the car will be high with the less age of the car. As expected, this diagram shows negative relationship and is approximately linear which does not shows positive relation between price and age.