Arnav scored 63 marks in English, 57 in Hindi, 82 in Mathematics, 55 in Social Science and x in Science. If the average he scored is 60, find the average of best four of them.

Answer

To solve the problem step by step, we will first find the value of x (the marks scored in Science) and then calculate the average of the best four subjects.

### Step 1: Set up the equation for the average
The average score is given by the formula:
\[ \text{Average} = \frac{\text{Sum of all marks}}{\text{Number of subjects}} \]
In this case, the average is 60, and there are 5 subjects. Therefore, we can write:
\[ 60 = \frac{63 + 57 + 82 + 55 + x}{5} \]

### Step 2: Calculate the sum of known marks
Now, let's calculate the sum of the known marks:
\[ 63 + 57 + 82 + 55 = 257 \]
So, we can rewrite the equation as:
\[ 60 = \frac{257 + x}{5} \]

### Step 3: Multiply both sides by 5
To eliminate the fraction, multiply both sides by 5:
\[ 300 = 257 + x \]

### Step 4: Solve for x
Now, isolate x:
\[ x = 300 - 257 \]
\[ x = 43 \]

### Step 5: List all the scores
Now we have all the scores:
- English: 63
- Hindi: 57
- Mathematics: 82
- Social Science: 55
- Science: 43

### Step 6: Identify the best four scores
The scores in descending order are:
- Mathematics: 82
- English: 63
- Hindi: 57
- Social Science: 55
- Science: 43

The best four scores are:
- 82, 63, 57, and 55.

### Step 7: Calculate the average of the best four scores
Now we can calculate the average of the best four scores:
\[ \text{Average of best four} = \frac{82 + 63 + 57 + 55}{4} \]
Calculating the sum:
\[ 82 + 63 + 57 + 55 = 257 \]
Now, divide by 4:
\[ \text{Average} = \frac{257}{4} = 64.25 \]

### Final Answer
The average of the best four subjects is:
\[ \boxed{64.25} \]