Your math test scores are 68, 78, 90, and 91. what is the lowest score you can earn on the next test and still achieve an average of at least 85?

Assuming the grade won't be rounded up or down to the nearest whole point, our cumalitive points would have to add up to 425. We can find this by multiplying the average we want (85%) by the total possible points (500).

.85*500=425

We then create this equation where x=fifth test score.

68+78+90+91+x=85

Then solve for x.

68+78+90+91+x=425
327+x=425
x=98

Thus, the minimum score on the last test would have to be a 98 to achieve an average of 85.

However, if the final grade is rounded, the new average we have to achieve is actually an 84.5%. Just follow the same steps as before:

.845*500=422.5
68+78+90+91+x=422.5
327+x=422.5
x=95.5

So in that scenario, you would be able to squeeze by with a 95.5 on that test.