# The aim of this investigation is to find out what influences the price of used cars (second hand). Used cars usually cost less than brand new cars, but this can be affected by hypotheses' such as mileage, age, colour, how it has been used etc.

Cherry Robinson 10/79                                                        15/06/2007

Maths Coursework:

Strand one:

Aim:

The aim of this investigation is to find out what influences the price of used cars (second hand). Used cars usually cost less than brand new cars, but this can be affected by hypotheses’ such as mileage, age, colour, how it has been used etc. My investigation is to find out how these hypotheses affect a used cars’ price.

Hypotheses:

For my example I have chosen to use the hypotheses: 1: age, 2: mileage, 3: weather it was expensive when new and 4: make. I have chosen these because I think they are most likely to affect the price of used cars.

Sample:

Out of my database of 150 I need to randomly select at least 30 samples. Samples are used representatively. They represent the whole database. We use samples because it would take too long to investigate every piece of data on the database, so we only investigate the samples. This is acceptable because they are selected randomly.

The samples are very poor because there was a database of 150 and only 30 samples. The probability of getting a common car (i.e. Ford) is higher than less common cars (i.e. Mercedes)

Testing hypotheses one.

I’d expect to find negative correlation. But vintage cars might be worth more as they get older. Good condition old cars might be worth more when older. New cars that are written off might be worth less than others of the same age.

The way I am getting my random samples, for this hypothesis, is by using my calculator because the human mind is unable to select things randomly.

I do this by tapping the second function key on my calculator and then pressing the random key. Then I multiply this by 150 (my database) and record the number it gives (rounding the number up if it’s a decimal). If the calculator gives the same number twice I must disregard it because it can bias my result.

Limitations of sampling are: The calculator gives the same number twice.

##### Sample

My calculator did get the same number twice. Because it could bias my result I disregarded it and used the next random number as my sample.

The graph shows negative correlation. This generally shows older cars are cheaper. Some cars of the same age cost different prices, this can be affected by other hypotheses.

Sub hypotheses:

Some cars used prices are affected by their price when new. We can show this by working out the percent knocked ...