Answer:
The 27th term is 73.5.
Step-by-step explanation:
We want to find the 27th term of the arithmetic sequence:
15, 17.25, 19.5, 21.75, ...
We can write a direct formula. Recall that the direct formula for an arithmetic sequence is given by:

Where <em>a</em> is the initial term and <em>d</em> is the common difference.
From the sequence, we can see that our initial term <em>a</em> is 15.
To find the common difference, subtract a term and its previous term. Thus, the common difference will be:

Thus, our direct formula is:

To find the 27th term, let <em>n</em> = 27. Substitute and evaluate:

Thus, the 27th term is 73.5.