In a class of 40 students, 10 have failed and their average marks are 30. The total marks obtained by the entire class are 3000. The average marks of those who have passed is

Options

A. 280
B. 2520
C. 90
D. None of these

Answer

To find the average marks of the students who have passed, we can follow these steps:

### Step 1: Determine the total marks obtained by the students who failed.
Given that there are 10 students who failed and their average marks are 30, we can calculate their total marks as follows:

\[ \text{Total marks of failed students} = \text{Number of failed students} \times \text{Average marks of failed students} \]

\[ \text{Total marks of failed students} = 10 \times 30 = 300 \]

### Step 2: Determine the total marks obtained by the entire class.
We know that the total marks obtained by the entire class of 40 students is given as 3000.

### Step 3: Calculate the total marks obtained by the students who passed.
To find the total marks obtained by the students who passed, we subtract the total marks of the failed students from the total marks of the entire class:

\[ \text{Total marks of passed students} = \text{Total marks of entire class} - \text{Total marks of failed students} \]

\[ \text{Total marks of passed students} = 3000 - 300 = 2700 \]

### Step 4: Determine the number of students who passed.
Since there are 40 students in total and 10 have failed, the number of students who passed is:

\[ \text{Number of passed students} = 40 - 10 = 30 \]

### Step 5: Calculate the average marks of the students who passed.
Now, we can find the average marks of the students who passed by dividing the total marks of the passed students by the number of passed students:

\[ \text{Average marks of passed students} = \frac{\text{Total marks of passed students}}{\text{Number of passed students}} \]

\[ \text{Average marks of passed students} = \frac{2700}{30} = 90 \]

### Final Answer:
The average marks of those who have passed is **90**.

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