Reading a histogram
A histogram shows how data are grouped into intervals, called bins. The height of each bar tells how many values fall in that interval. To read one correctly, focus on the horizontal axis for the intervals and the vertical axis for the frequency or count.
Steps
- Identify the bin interval. Read the interval written under each bar or along the axis.
- Read the bar height. Match the top of the bar to the vertical scale.
- State the frequency. The height gives the number of data values in that interval.
- If asked for a total, add the frequencies. Sum the counts from the relevant bars.
- Simplify your final answer. If you combine counts, write the reduced total clearly.
Good checks
- Make sure you are using the correct scale on the vertical axis.
- Do not confuse a histogram with a bar graph: histogram bars usually touch because the intervals are continuous.
- If a question asks for “between” values, include only the bins that match the interval shown.
Final check
Your answer should be a count or total that matches the bar heights exactly.