If there are 5 terms, the first is 2 and the last term is 4, find the common difference.

0.5

Step-by-step explanation:

Let's imagine the terms like this:

2,?,?,?, 4

Pretend they're on a number line, then use the guess and check method. We know that the number must be less than 1, because there are 4 tics between 2 and 4 (including 4's tic) and 2 + 4 is not equal to 4. We know that it is greater than 0 because 2 and 4 are both positive. Using this logic, try 0.5. Add 0.5 to 2, the term after 2, and so on.

2, 2.5, 3, 3.5, 4

It is valid, therefore the common difference is 0.5.