In a class, there are 30 boys and 20 girls. The average weight of 30 boys is 60 kg and average weight of 20 girls is 35 kg. Find the average weight of the class.

Options

A. 40 kg
B. 50 kg
C. 60 kg
D. 45 kg

Explanation

To find the average weight of the class, we will follow these steps:

### Step 1: Calculate the total weight of the boys.
The average weight of the boys is given as 60 kg, and there are 30 boys.

\[ \text{Total weight of boys} = \text{Number of boys} \times \text{Average weight of boys} \]
\[ \text{Total weight of boys} = 30 \times 60 = 1800 \text{ kg} \]

### Step 2: Calculate the total weight of the girls.
The average weight of the girls is given as 35 kg, and there are 20 girls.

\[ \text{Total weight of girls} = \text{Number of girls} \times \text{Average weight of girls} \]
\[ \text{Total weight of girls} = 20 \times 35 = 700 \text{ kg} \]

### Step 3: Calculate the total weight of the class.
Now, we will add the total weight of the boys and the total weight of the girls.

\[ \text{Total weight of class} = \text{Total weight of boys} + \text{Total weight of girls} \]
\[ \text{Total weight of class} = 1800 + 700 = 2500 \text{ kg} \]

### Step 4: Calculate the total number of students in the class.
The total number of students is the sum of the number of boys and girls.

\[ \text{Total number of students} = \text{Number of boys} + \text{Number of girls} \]
\[ \text{Total number of students} = 30 + 20 = 50 \]

### Step 5: Calculate the average weight of the class.
Finally, we will find the average weight of the class by dividing the total weight of the class by the total number of students.

\[ \text{Average weight of class} = \frac{\text{Total weight of class}}{\text{Total number of students}} \]
\[ \text{Average weight of class} = \frac{2500}{50} = 50 \text{ kg} \]

### Final Answer:
The average weight of the class is **50 kg**.

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