Math Chapter 10.1

Calculating Statistics

You can use statistics to summarise sets of data.
You can also use them to compare different sets of data.

You should already be able to calculate three different averages:

• the mode
• the median, and
• the mean.

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

Example:

The table shows the number of beads on 200 necklaces.

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

 
a. find the mode.
b. find the mean.
c. find the range.


Answer:

a. the mode is 35.               
 ---> the mode number is the number with the highest frequency.


b. 6900 : 200 = 34.5         
 ---> (25 x 34) + (30 x 48) + (35 x 61) + (40 x 30) + (45x15) + (50  x 12) : the sum of all the frequencies

c. 50 - 25 =  25                
 ---> This is difference between the largest and smallest number of beads.