Mean Grouped Data 91E62E
1. The problem involves calculating the mean ($\bar{x}$) from grouped frequency data.
2. The formula for the mean of grouped data is:
$$\bar{x} = \frac{\sum f_i x_i}{\sum f_i}$$
where $f_i$ is the frequency of the $i$th class and $x_i$ is the midpoint of the $i$th class interval.
3. From the table, the class intervals and frequencies ($f$) are:
- 8-18 with $f=4$
- 12-17 with $f=8$
- 18-29 with $f=10$
4. Calculate the midpoints ($x_i$) of each class:
- For 8-18: $x_1 = \frac{8+18}{2} = 13$
- For 12-17: $x_2 = \frac{12+17}{2} = 14.5$
- For 18-29: $x_3 = \frac{18+29}{2} = 23.5$
5. Multiply each midpoint by its frequency:
- $4 \times 13 = 52$
- $8 \times 14.5 = 116$
- $10 \times 23.5 = 235$
6. Sum the products and frequencies:
- $\sum f_i x_i = 52 + 116 + 235 = 403$
- $\sum f_i = 4 + 8 + 10 = 22$
7. Calculate the mean:
$$\bar{x} = \frac{403}{22} \approx 18.32$$
Therefore, the mean $\bar{x}$ is approximately 18.32.