These are the selling prices of 5 houses in 2007: £145 000, £170 000, £215 000, £90 000, £180 000 (a) Work out the mean selling price.

The mean is also known as the average. To work out the mean you need to add all the house prices together and then divide by the number of houses. So in this example the total price of the houses is 145000+170000+215000+90000+180000= 800000. Then you divide 800000 by the number of houses (5) which gives you a mean of  £160,000.