A student obtain `75%, 80% and 85%` in three subjects if the marks of another subject are added. Then the average cannot be less than

Options

A. 0.6
B. 0.65
C. 0.8
D. 0.9

Explanation

To solve the problem step by step, we will follow these instructions:

### Step 1: Calculate the total marks obtained in the three subjects.
The student has obtained the following percentages in three subjects:
- Subject 1: 75%
- Subject 2: 80%
- Subject 3: 85%

Assuming each subject is out of 100 marks, we can calculate the total marks obtained in these three subjects.

\[ \text{Total Marks} = 75 + 80 + 85 = 240 \]

### Step 2: Consider the addition of a fourth subject.
We need to find the average when a fourth subject is added. To find the minimum possible average, we will assume the student scores the lowest possible marks in the fourth subject, which is 0%.

### Step 3: Calculate the average with the fourth subject.
Now, we will calculate the average of the four subjects:

\[ \text{Total Marks with Fourth Subject} = 240 + 0 = 240 \]

The average marks can be calculated as follows:

\[ \text{Average} = \frac{\text{Total Marks}}{\text{Number of Subjects}} = \frac{240}{4} \]

Calculating this gives:

\[ \text{Average} = 60 \]

### Step 4: Convert the average to percentage.
Since the average is calculated out of 100, we can express it as a percentage:

\[ \text{Average Percentage} = 60\% \]

### Conclusion:
The minimum average percentage that the student can achieve, even with the lowest score in the fourth subject, is **60%**.