# Maths Coursework:Used Cars

Introduction:

In this coursework I will be investigating the most popular cars and factors that may have an effect on the price of the second hand cars. I will investigate the following factors:

• Age of the car
• Mileage
• Engine size
• New price

Aim:

My aim is to see if the above factors affect the second hand price and if they affect the popularity of the cars.

Hypothesis:

• As the mileage increases the second hand price will decrease.
• The bigger the engine size the higher the price of the second hand car.
• The older the car the cheaper it will be.

I will be using scatter diagrams to show the correlation. I will also use box and whiskers to show the median and compare the ranges of second hand price. I expect all four hypotheses to be correct because logically if the mileage increases the price of the car should automatically decrease. It is the same for the rest of the hypotheses.

Now I will do stratified sample to find the 4 most popular cars. I am using this method because it is fair and unbiased.

Using this pie chart I have decided that the four most popular cars are Vauxhall, fiat, ford and rover. This is because these cars are most common cars in the population and the other cars have single models so the results will not be reliable. Also the size of the database is very small and if I could do the survey I would choose a much bigger database.

Stratified sampling

I will use the four most popular cars in order to carry out the stratified sampling.

If I used all the cars in the population it would be unfair because the four makes have different amount of cars. The method of sampling I will use is fair and easy to do. My chosen sample size is 40 because nothing less than 30 gives reliable results. The formula I will be using is:

Car make = Total no. of car make x Sample size

Total no. of cars

Ford = 16*40 = 13

51

Vauxhall= 13*40 = 10

51

Rover = 12*40 = 9

51

Fiat = 10*40 =8

51

I used stratified sampling because every group is represented in an identical amount. So I can get a good representation of the complete population. The main reason why I used sampling was it reduces the time taken to process and also it will avoid bias and be fairer.

Random Sampling

Ford

3rd                                                                                                       ...