Averages
The value of stock was then calculated, in total and by make. From these values the Mean Average, Mode Average and the Median Average was calculated for the total stock. Due to the small number of samples in the groups of make only the mean was calculated.
The mean value of Fiat cars in stock = £12,000 divided by 3 = £4,000
The mean value of Ford cars in stock = £50,140 divided by 12 = £4,178.33
The mean value of Peugeot cars in stock = £25,900 divided by 6 = £4,316.67
The mean value of Rover cars in stock = £30,395 divided by 6 = £5,065.83
The mean value of Vauxhall cars in stock = £45,595 divided by 9 = £5,066.11
The total value of stock is £164,030
The mean value of the total stock = £164,030 divided by 36 = £4,556.39
The median value of the total stock was then calculated using the table of ordered prices below:
Because there isn’t a middle value (due to the fact there is 36 cars) the two middle values are added together and divided by 2. The two values to be used are 18th & 19th in the ordered list, car 22 (£4,600) & car 24 (£4,800).
The median value of the total stock = (£4,600 + £4,800) divided by 2 = £4,700
The mode value (most frequent) of the total stock = £5,595 & £4,995 (2 each).
The range of the total stock =
Highest value (£750) – Lowest value (£11,000) = £10,250
The percentages of stock by make where then calculated:
Fiat £12,000 as a percentage of £164,030 =
(£12,000 divided by £164,030) x 100 = 7.3%
Ford £50,140 as a percentage of £164,030 =
(£50,140 divided by £164,030) x 100 = 30.5%
Peugeot £25,900 as a percentage of £164,030 =
(£25,900 divided by £164,030) x 100 = 15.8%
Rover £30,395 as a percentage of £164,030 =
(£30,395 divided by £164,030) x 100 = 18.6%
Vauxhall £45,595 as a percentage of £164,030 =
(£45,595 divided by £164,030) x 100 = 27.8%
The information above was then used to construct a pie chart that represents the percentage of stock by make:
Identifying Trends
Below various attributes of each car are compared to identify any trends in the price of the various cars held in stock.
Mileage v Age.
The table below shows the data used to plot the scatter chart of Mileage v Age. Car 3 was exclude from the chart as its excessive age would skew the age scale. The scatter chart has a linear trend line drawn to show the trend that older cars tend to have higher mileage.
Depreciation
The table below shows the following given information Car No, Age, Mileage, Price & Cost When New. The following information has been calculated and added:
Difference = Cost When New – Price
% Depreciation = (100 / Cost When New) x Difference
Current £ as % of New = (100 / Cost When New) x Price
From the above table the following charts have been plotted:
Depreciation v Age
The scatter graph below shows a plot of Depreciation against Age. Car 3 has been left out as it distorts the scale. A trend line has been added to show the depreciation trend.
Depreciation v Mileage
The scatter graph below shows a plot of Depreciation against Mileage. A trend line has been added to show the depreciation trend.
The trend lines on the scatter graphs for both Age & Mileage against % depreciation seem to follow a similar curve. The reason for this can be explained by the linear relationship between Age and mileage that was identified in the scatter graph Age v Mileage.
Depreciation per Year v Age:
Depreciation per Year has been calculated by dividing % depreciation by the age of a car, the table below displays the results.
The scatter graph below shows Depreciation Per Year v Age. A trend line has been added.
Depreciation by Make
The table below shows % Depreciation per Year ordered by Make
The mean average % depreciation for the stock of cars is 14.19%.
The mean average % depreciation per year for each Make is as follows:
Fiat
(8.43 + 15.85 + 11.38) divided by 3
=11.89%
Ford
(13.30 + 1.62 + 9.81 + 8.87 + 12.28 + 16.48 + 15.01 + 10.65 + 10.42 + 13.10 + 12.95 + 19.42) divided by 12
=11.99%
Peugeot
(7.55 + 8.39 + 7.75 + 20.29 + 25.71 + 10.84) divided by 6
=13.42%
Rover
(14.14 + 11.19 + 18.49 + 26.03 + 34.25 + 15.48) divided by 6
=19.93%
Vauxhall
(11.25 + 9.20 + 10.16 + 23.29 + 9.64 + 16.44 + 13.48 + 22.35 + 15.21) divided by 9
=23.44%
The bar chart shows the Mean % Depreciation per year by Make of car.
