给定一组整数，请编写一个函数，用于计算这些整数的平均值。


Numbers: [2, 5, 8, 11, 14]
函数定义：

```python
def calc_average(numbers):
    return sum(numbers) / len(numbers)
```

调用函数：

```python
numbers = [2, 5, 8, 11, 14]
average = calc_average(numbers)
print("Average is:", average)
```

输出结果：

```
Average is: 8.0
```