In Chemistry class Andrew has earned scores of 64 69 and 73 on three tests. He must maintain an average 70 to pass the course. What score earn final exam course?

Let $s_1, s_2, s_3, s_4$ be the scores Andrew earned on the three tests and the final exam, respectively.

The scores on the three tests are $s_1 = 64$, $s_2 = 69$, and $s_3 = 73$.

The average of the four scores must be at least 70 to pass the course.

The average of the four scores is given by:

$$ \text{Average} = \frac{s_1 + s_2 + s_3 + s_4}{4} $$

We want the average to be at least 70, so we have:

$$ \frac{s_1 + s_2 + s_3 + s_4}{4} \ge 70 $$

Substituting the given scores:

$$ \frac{64 + 69 + 73 + s_4}{4} \ge 70 $$

$$ \frac{206 + s_4}{4} \ge 70 $$

Multiply both sides by 4:

$$ 206 + s_4 \ge 280 $$

Subtract 206 from both sides:

$$ s_4 \ge 280 - 206 $$

$$ s_4 \ge 74 $$

Therefore, Andrew must earn at least a score of 74 on the final exam to maintain an average of 70 or higher.

Final Answer: The final answer is $\boxed{74}$