10.1 Calculating Statics

You can use statistics to summarise sets of data.

You can also use to compare different sets of data.

You should already be able to calculate three different averages: 

The Mode, The Median, The Mean

Remember that the range is not an average. It measures how spread out a set of value or number is. For a large set od data, it is not practical to list every number separetly. Instead, you can record the data in frequency table.

The Mode is the most common value or number.

The Median is the middle value, when they are listed in order.

The Mean is the sum of all the values divided by the number of values.

The Range is the largest value minus the smallest.

WORKED EXAMPLE:

Number of Beads	25	30	35	40	45	50
Frequency	34	48	61	30	15	12

The tables shows the number of beads on 200 necklaces.

a) Find the mode

b) Find the mean

c) Find the range

ANSWER:

a) The Mode is 35   

    --> The mode is the number with the highest frequency

b) 6900 / 200 = 34.5 

   --> (25 x 34 + 30 x 48 + 35 x 61 + 40 x 30 + 45 x 15 + 50 x 12 ) divided by the sum of all frequencies.

          This is the middle of all the possible number of beads.

c) 50 - 25 = 25

  --> This is the difference between the largest and the smallest number of beads