Insert four arithmetic mean (AM) between 4 and 19.

Explanation

To insert four arithmetic means between 4 and 19, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the given numbers**: The first number (a) is 4, and the last number (l) is 19. We need to insert 4 arithmetic means between them.

2. **Determine the total number of terms**: Since we are inserting 4 arithmetic means between 4 and 19, the total number of terms in the series will be:
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