Probability and statistics - Maths

Mean

Adds up all the values and divides the answer by the total number of values. The answer shouldn’t be rounded.

Median

Takes the middle value of a data set in order increasing size.

• If there is an even set of values:

  • The median is halfway between the two values

• If there is an odd set of values:

  • The median is the middle value.

Mode

Looks for the most common value

• If there is a value with the highest frequency:

  • The value is the mode

• If There is more then one value with the highest frequency:

  • The mode is all the values.

• If all values have the same frequency:

  • Either there is no mode or the mode is all the values.

How to find out removed cards

1. Read the question and multiply the given mean by the number of cards left.

2. Take the mean of the cards and and take it away from the lower mean of the removed cards

3. Take two of the cards which add up to the total.

Advantages and disadvantages of the mean

Advantage:

• Uses all of the data.

Disadvantage:

• Affected by extreme values.

Advantages and disadvantages of the median

Advantage:

• Not affected by extreme values.

Disadvantage:

• Value may not exist.

Advantage and disadvantage of the mode

Advantage:

• Suitable for data that can be described in words.

Disadvantage:

• Not always near the middle of the data.

How to find the mean in a frequency table

1. Make sure that the total frequency is given to you. If not, Add the frequencies together.

2. Multiply the number by the frequency and extend the table.

3. To find the mean divide the total number by the total frequency

Quartiles

Divide a set into four equal parts.

Range

Largest value - smallest value.