https://file.aiquickdraw.com/mathbot/file/1729860213856pyojw7e2.jpg

Let's break down and solve the two tasks shown in the image.

### 1. Finding the Mean Weight from the Data:
The problem asks to determine the average (mean) weight from the data set given for 30 students.

**Step 1: List of Weights**  
The data set contains the following weights (in kg):

40, 45, 50, 45, 91, 43,  
42, 50, 52, 47, 43, 52,  
45, 49, 50, 46, 48, 47,  
49, 48, 47, 46, 47, 50,  
49, 47, 43, 49, 43, 45.

**Step 2: Calculate the Mean**
To calculate the mean, sum all the weights and then divide by the total number of students (30).

\[
\text{Mean} = \frac{\sum \text{weights}}{30}
\]

First, calculate the sum:
\[
40 + 45 + 50 + 45 + 91 + 43 + 42 + 50 + 52 + 47 + 43 + 52 + 45 + 49 + 50 + 46 + 48 + 47 + 49 + 48 + 47 + 46 + 47 + 50 + 49 + 47 + 43 + 49 + 43 + 45 = 1384
\]

Now, divide by 30:
\[
\text{Mean} = \frac{1384}{30} = 46.13 \, \text{kg}
\]

So, the mean weight is approximately **46.13 kg**.

### 2. Finding the Mean from the Frequency Table:
The table provides the scores and their frequencies for a class, and we need to calculate the mean score.

| Score (Nilai Siswa) | Frequency (Frekuensi) |
|---------------------|-----------------------|
| 60                  | 2                     |
| 65                  | 3                     |
| 70                  | 4                     |
| 75                  | 5                     |
| 80                  | 3                     |
| 85                  | 4                     |
| 90                  | 5                     |
| 95                  | 4                     |
| 100                 | 2                     |

**Step 1: Calculate the sum of products of scores and their frequencies**  
To calculate the weighted sum of the scores, multiply each score by its frequency:

\[
(60 \times 2) + (65 \times 3) + (70 \times 4) + (75 \times 5) + (80 \times 3) + (85 \times 4) + (90 \times 5) + (95 \times 4) + (100 \times 2)
\]

\[
= 120 + 195 + 280 + 375 + 240 + 340 + 450 + 380 + 200 = 2580
\]

**Step 2: Sum of frequencies**  
The total number of students is the sum of the frequencies:

\[
2 + 3 + 4 + 5 + 3 + 4 + 5 + 4 + 2 = 32
\]

**Step 3: Calculate the Mean**  
Now, divide the weighted sum by the total frequency to find the mean:

\[
\text{Mean} = \frac{2580}{32} = 80.625
\]

Thus, the mean score is approximately **80.63**.

---

Would you like further clarification or details on any part of the solution? Here are some follow-up questions related to this task:

1. How do we interpret the mean in terms of weight distribution for the class?
2. Why is it important to consider frequency when calculating the mean from a table?
3. How does the frequency distribution affect the overall mean in problem 2?
4. What other statistical measures could be used to analyze this data set?
5. Can you describe the significance of outliers in a data set like the one in problem 1?

**Tip:** When working with large data sets, organizing data systematically (like using frequency tables) helps make calculations much easier!

Find the mean (average) from a set of weights of 30 students and calculate the mean from a frequency table showing student scores.

Learn how to calculate the mean weight of 30 students and the mean of student scores from a frequency table. This problem covers key mathematical concepts, including averages and frequency table calculations, suitable for Grade 8 students.

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