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Chapter overview
Learning goals
Learning Goals
Maths
Summary
Just like for sets of values, the mean, median, mode and range can be found from frequency tables too. The only difference is that these averages might refer to a category, rather than an individual number.
Mean | Create a new column: 'number $\times$ frequency' and calculate these values. Next, find the sum of all these values, then divide this number by the total frequency. |
Median | Identify the category containing the middle value: use $\frac{n+1}{2}$ where n is the total frequency to find the middle position. |
Mode | Identify the category with the highest frequency. |
Range | Calculate the difference between the highest and lowest in the 'number of' column. |
This frequency table shows the number of siblings pupils in a class of $23$ have:
Number of siblings | Frequency |
$0$ | $6$ |
$1$ | $12$ |
$2$ | $3$ |
$3$ | $2$ |
$4$ | $0$ |
Find the mean, median, range and mode.
1. Mean:
Add the third column to the table.
Number of siblings $\times$ frequency |
$0\times6=0$ |
$1\times12=12$ |
$2\times3=6$ |
$3\times2=6$ |
$4\times0=0$ |
Use the formula:
$\frac{\text{sum of 'number}\times \text{frequency' column}}{\text{total frequency}}=\frac{12+6+6}{6+12+3+2}=\frac{24}{23}=\underline{1.043} \text{ (to 3 d.p})$
Note: The total number of students was given in the question here, but often you will need to calculate it yourself.
2. Median:
Identify the middle position.
$\frac{(n+1)}{2}=\frac{(23+1)}{2}=12$
The median is the category containing the $12th$ value cumulatively: $\underline1$
3. Mode:
Identify the category with the highest frequency.
$\underline1$
4. Range:
Work out the difference between the highest and lowest number of siblings.
$3-0 = \underline3$
Note: $4$ is not used here as there is no one with $4$ siblings.
Just like for sets of values, the mean, median, mode and range can be found from frequency tables too. The only difference is that these averages might refer to a category, rather than an individual number.
Mean | Create a new column: 'number $\times$ frequency' and calculate these values. Next, find the sum of all these values, then divide this number by the total frequency. |
Median | Identify the category containing the middle value: use $\frac{n+1}{2}$ where n is the total frequency to find the middle position. |
Mode | Identify the category with the highest frequency. |
Range | Calculate the difference between the highest and lowest in the 'number of' column. |
This frequency table shows the number of siblings pupils in a class of $23$ have:
Number of siblings | Frequency |
$0$ | $6$ |
$1$ | $12$ |
$2$ | $3$ |
$3$ | $2$ |
$4$ | $0$ |
Find the mean, median, range and mode.
1. Mean:
Add the third column to the table.
Number of siblings $\times$ frequency |
$0\times6=0$ |
$1\times12=12$ |
$2\times3=6$ |
$3\times2=6$ |
$4\times0=0$ |
Use the formula:
$\frac{\text{sum of 'number}\times \text{frequency' column}}{\text{total frequency}}=\frac{12+6+6}{6+12+3+2}=\frac{24}{23}=\underline{1.043} \text{ (to 3 d.p})$
Note: The total number of students was given in the question here, but often you will need to calculate it yourself.
2. Median:
Identify the middle position.
$\frac{(n+1)}{2}=\frac{(23+1)}{2}=12$
The median is the category containing the $12th$ value cumulatively: $\underline1$
3. Mode:
Identify the category with the highest frequency.
$\underline1$
4. Range:
Work out the difference between the highest and lowest number of siblings.
$3-0 = \underline3$
Note: $4$ is not used here as there is no one with $4$ siblings.
Averages from frequency tables
FAQs
Question: How do I find the range from a frequency table?
Answer: To find the range from a frequency table, find the difference between the highest and lowest in the 'number of' column.
Question: How do I find the mode from a frequency table?
Answer: The mode in a frequency table is the value of the category with the highest frequency.
Question: How do I find the median from a frequency table?
Answer: To find the mean from a frequency table, find the category containing the middle value: use (n+1)÷2 where n is the total frequency to find the middle position.
Question: How do I find the mean from a frequency table?
Answer: To find the mean from a frequency table: Create a new column: 'number × frequency' and calculate these values. Next, find the sum of all these values, then divide this number by the total frequency.
Theory
Exercises
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