Rod's quiz grades are 72, 74, 89, and90. What score on a fifth quiz will make his average woz grade at least 84?

Answer: He would need at least a 95

Step-by-step explanation:

First I found the current average by adding 72, 74, 89, and 90 which equals 325.

Second, I worked backwards to see what the sum of his grades had to be by multiplying 84 times 5. 84 times 5 = 420

Now that we have both the current and the target sum, we find the difference by doing 420-325 which equals 95.