Mode, median and range · Usually met around P5
Dot plots
A dot a value; the tallest column is the mode.
How to do it
Method
A dot a value; the tallest column is the mode
4 dots over 3: 3 appears 4 times
Another way
Write it as a list
●● ●●● → 1, 1, 2, 2, 2
In full
A dot plot puts one dot over a number line for each piece of data, equal values stacked. Count a column's dots to see how often that value appears; all the dots together are how many values there are. The tallest column is the mode (give the value under it, not the number of dots). The range is the rightmost value with a dot minus the leftmost, not the ends of the line. The median: count dots from the left to the middle dot and see which value it sits on. Another way: write the plot back out as a list, then work as usual.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
The dot plot shows how many brothers and sisters some friends each have; each dot is 1 person. How many have 3?
Show the answer and working
Answer: 3
Count the dots over 3: 3 dots, so 3 people.
Example 2
The dot plot shows how many times some friends went swimming in a month; each dot is 1 person. What is the range?
Show the answer and working
Answer: 6
The largest value with a dot is 9, the smallest 3: 9 − 3 = 6. Values with no dots don't count.
Example 3
The dot plot shows how many bicycles some families each have; each dot is 1 family. What is the median number of bicycles?
Show the answer and working
Answer: 2
15 dots in all; the middle one is the 8th. Counting from the left, the 8th dot sits over 2.
Practise it in the game →Mode, median and range · Free to start, unlimited questions, no download