Score Frequency
1. **Problem Statement:** We have a frequency distribution of scores in intervals and their corresponding frequencies. We want to understand the data and possibly find measures like the mean or visualize it.
2. **Data Given:**
- Scores intervals: 46-50, 41-45, 36-40, 31-35, 26-30, 21-25
- Frequencies: 4, 6, 10, 8, 12, 5 respectively
3. **Step 1: Find the midpoints of each score interval.**
The midpoint $m$ of an interval $[a,b]$ is given by:
$$m = \frac{a+b}{2}$$
Calculate midpoints:
- $\frac{46+50}{2} = 48$
- $\frac{41+45}{2} = 43$
- $\frac{36+40}{2} = 38$
- $\frac{31+35}{2} = 33$
- $\frac{26+30}{2} = 28$
- $\frac{21+25}{2} = 23$
4. **Step 2: Use midpoints and frequencies to find the mean score.**
The formula for mean of grouped data is:
$$\bar{x} = \frac{\sum (f_i \cdot m_i)}{\sum f_i}$$
where $f_i$ is frequency and $m_i$ is midpoint.
Calculate numerator:
$$4 \times 48 + 6 \times 43 + 10 \times 38 + 8 \times 33 + 12 \times 28 + 5 \times 23$$
$$= 192 + 258 + 380 + 264 + 336 + 115 = 1545$$
Calculate denominator:
$$4 + 6 + 10 + 8 + 12 + 5 = 45$$
Calculate mean:
$$\bar{x} = \frac{1545}{45} = 34.33$$
5. **Interpretation:** The average score is approximately 34.33.
6. **Additional:** The bar graph described shows frequencies on the y-axis and score intervals on the x-axis, matching the frequency table.
This analysis helps understand the distribution and central tendency of the scores.