used car coursework

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Sukhraj Dhillon

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Used car coursework

This coursework is about what influences the price of a second hand car. In this coursework I will be comparing the second hand prices of cars, using different factors. There will be tables and graphs showing the four most popular cars. I will be writing about how mileage, age, used car price and engine size of different cars affect their second hand prices. This will help me show which car has the biggest depreciation rate.    

My hypotheses are:

  1. As the mileage increases the second hand price will decrease.
  2. The bigger the engine size the higher the price of the second hand car.
  3. The older the car the cheaper it will be.
  4. The higher the price of the car when brought the less it depreciates.

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.

Stratified sampling

I choose the four most popular cars in order to conduct the stratified sampling.

The method of sampling I will use is fair and easy to do. My chosen sample size is 35. The formula I will b using is:

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

                       Total no. of cars

Ford = 16   x  35 = 11

            51

Vauxhall =  13   x  35 =  8

                    51

Rover =  12   x  35 = 8

               

               51

Fiat =  10   x  35 =7

           

           

            51

I used stratified sampling because every group is represented in an identical quantity. So I can get a good representation of the complete population. The main reason why I used sampling was as it reduces the time taken to process.

Scatter diagram work

This table shows the 11 Ford cars out of 16 which were selected through stratified sampling. The table shows the cars mileage, age, used car price and engine size.

This scatter diagram shows the affect on the used car price as the age increases. I added a trend line and it goes in a down ward slope from left to right. This indicates to us that the graph is showing us a negative correlation between the used car price and the age. From the graph I can say that the older the car is the lower the value is of the car. The equation of the line is:

y = - 649.6x + 7137.1

The gradient is -649.6 and this tells us that every time the age of the car increases by 1 year the value of the car decreases by £649.60. The intercept of the line is 7137.1 and this tells us that if the car had an age of 0 years then the price would be £7137.1.

This scatter diagram shows the affect on used car price as the mileage increases. The trend line I added shows a slope going downwards from left to right. It shows a negative correlation between used car price and mileage. From the graph I can say that as the mileage increases the used car price decreases. The equation of the line is:

y = - 0.07704 + 6612.5

The gradient is -0.07704 and this tells us that every time the mileage increases by 1 mile the used car price will decrease by £0.07. The intercept of the line is 6612.5 and this tells us that if the mileage is 0 then the used car price will be £6612.5.

This scatter diagram shows the affect on used car price as the engine size increases. The trend line I added shows a slope going upwards from left to right. It shows a positive correlation between used car price and engine size. From the graph I can say that as the engine size increases the used car price increases. The equation of the line is:

y = 3967.9x – 2476.1

The gradient is 3967.9 and this tells us that every time the engine size increases by 1 the used car price will increase by £3967.90. The intercept of the line is -2476.1 and this tells us that if the mileage is 0 then the used car price will be -£2476.1.

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This table compares the used car price to the new car price of Ford cars.

This scatter diagram compares the new car price against the used car price of Ford cars. The trend line I added shows a slope going upwards from left to right. It shows a positive correlation between new car price and used car price. From the graph I can say that as the used car price increases the new car price increases. The ...

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