Question: Histogram with x-axis labeled $\text{data}$ and y-axis labeled $\text{Frequency}$; bars span approximately $1$–$3$ (height $8$), $3$–$5$ (height $7$), $5$–$7$ (height $6$), $7$–$9$ (height $10$), $9$–$11$ (height $3$), and $11$–$13$ (height $5$), located top-left.
Based on the histogram above, what is the class width?
Class width =
What is the sample size?
Sample size =
1. **State the problem:** We are given a histogram with class intervals and their frequencies. We need to find the class width and the sample size.
2. **Find the class width:** The class width is the difference between the upper and lower boundaries of any class interval.
For example, consider the first class interval: $1$ to $3$.
$$\text{Class width} = 3 - 1 = 2$$
This is consistent for all intervals: $3$–$5$, $5$–$7$, etc., each has width $2$.
3. **Find the sample size:** The sample size is the total frequency, which is the sum of the heights of all bars.
$$\text{Sample size} = 8 + 7 + 6 + 10 + 3 + 5 = 39$$
4. **Final answers:**
- Class width = $2$
- Sample size = $39$