The average weight of a class of 40 boys is 55 kg. The average weight is raised to 56 kg, if the weight of teacher is added, then the weight of the teacher in kg is

Options

A. 96
B. 111
C. 56
D. 76

Answer

To find the weight of the teacher, we can follow these steps:

### Step 1: Calculate the total weight of the 40 boys.
Given that the average weight of the boys is 55 kg and there are 40 boys, we can calculate the total weight using the formula:

\[ \text{Total Weight} = \text{Average Weight} \times \text{Number of Boys} \]

\[ \text{Total Weight} = 55 \, \text{kg} \times 40 = 2200 \, \text{kg} \]

### Step 2: Find the new total weight when the teacher is added.
When the teacher's weight is added, the average weight of the class increases to 56 kg. Now, the total number of individuals (boys + teacher) is 41. We can calculate the new total weight:

\[ \text{New Total Weight} = \text{New Average Weight} \times \text{Total Number of Individuals} \]

\[ \text{New Total Weight} = 56 \, \text{kg} \times 41 = 2296 \, \text{kg} \]

### Step 3: Calculate the weight of the teacher.
To find the weight of the teacher, we subtract the total weight of the boys from the new total weight:

\[ \text{Weight of Teacher} = \text{New Total Weight} - \text{Total Weight of Boys} \]

\[ \text{Weight of Teacher} = 2296 \, \text{kg} - 2200 \, \text{kg} = 96 \, \text{kg} \]

### Final Answer:
The weight of the teacher is **96 kg**.

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