What is the average of first 39 even numbers?

Options

A. 39
B. 40
C. 20
D. 68

Answer

To find the average of the first 39 even numbers, we can follow these steps:

### Step 1: Identify the first 39 even numbers
The first 39 even numbers are:
2, 4, 6, 8, ..., 78 (since the nth even number can be expressed as 2n).

### Step 2: Calculate the sum of the first 39 even numbers
The sum of the first n even numbers can be calculated using the formula:
\[ \text{Sum} = n \times (n + 1) \]
For our case, \( n = 39 \):
\[ \text{Sum} = 39 \times (39 + 1) = 39 \times 40 \]

### Step 3: Calculate the average
The average is calculated by dividing the sum by the number of terms:
\[ \text{Average} = \frac{\text{Sum}}{\text{Number of terms}} \]
Here, the number of terms is 39:
\[ \text{Average} = \frac{39 \times 40}{39} \]

### Step 4: Simplify the average
When we simplify the above expression:
\[ \text{Average} = 40 \]

### Conclusion
Thus, the average of the first 39 even numbers is **40**.

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