The average weight of class of 40 students is 35 kg. If one student leaves the class, the average weight of the class drops by 200 gm. What is the weight of that student?

Ops: A.37.4 kg

B. 44.6 kg

C. 39.2 kg

D. 42.8 kg

We are given that:

- The average weight of 40 students is 35 kg.
- When one student leaves, the average weight decreases by 200 grams (0.2 kg).
  
We need to determine the weight of the student who left the class.

### Step 1: Calculate the total weight of 40 students

The total weight \( W_1 \) of the 40 students can be calculated as:

\[
W_1 = \text{average weight} \times \text{number of students} = 35 \, \text{kg} \times 40 = 1400 \, \text{kg}
\]

### Step 2: Calculate the total weight of the remaining 39 students

When one student leaves, the new average weight becomes \( 35 \, \text{kg} - 0.2 \, \text{kg} = 34.8 \, \text{kg} \).

The total weight \( W_2 \) of the remaining 39 students is:

\[
W_2 = 34.8 \, \text{kg} \times 39 = 1357.2 \, \text{kg}
\]

### Step 3: Calculate the weight of the student who left

The weight of the student who left is the difference between the total weight of the 40 students and the remaining 39 students:

\[
\text{Weight of the student} = W_1 - W_2 = 1400 \, \text{kg} - 1357.2 \, \text{kg} = 42.8 \, \text{kg}
\]

Thus, the weight of the student who left is **42.8 kg**.

### Final Answer: 
The correct option is **D. 42.8 kg**.

Would you like more details on any step or have further questions?

Here are 5 related questions you could explore:
1. How does changing the number of students affect the average weight calculation?
2. What happens if multiple students leave the class?
3. How would the problem change if the student's weight increased the average?
4. How is the concept of weighted averages applied in different scenarios?
5. What is the mathematical importance of average and total weight in such problems?

**Tip:** When dealing with averages, always start by calculating the total sum, as this is often key to solving the problem.

The average weight of class of 40 students is 35 kg. If one student leaves the class, the average weight of the class drops by 200 gm. What is the weight of that student?

Solve the problem of finding the weight of a student who leaves a class of 40 students, where the average weight drops by 200 gm. Learn how to apply averages and simple arithmetic to calculate the result. Suitable for Grades 6-8.

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