Here is a link to the playlist of video explanations to all of the math questions in the 2019 December ACT (Form C03) Test.

Try this ACT math practice question on how to find the terms of an arithmetic progression.

In an arithmetic progression the difference between consecutive terms is a constant. For example, the sequence $3, 7, 11, 15, \ldots$ is an arithmetic progression where the consecutive terms are $4$ apart. If the first term of an arithmetic progression is $4$ and the last term is $54$, and the sum is $609$, then what is the third term?

1. $\quad 8$
2. $\quad 8.5$
3. $\quad 9$
4. $\quad 9.5$
5. $\quad 10$

Choice C