I need help!!!!!!!!!!

Mike's test grades are 78, 79, and 88. What is the lowest grade Mike can get on the next test and have an average of 80?

A. 78
B. 75
C. None of the choices are correct.

can someone explain me

Question

I need help!!!!!!!!!!

Mike's test grades are 78, 79, and 88. What is the lowest grade Mike can get on the next test and have an average of 80?

A. 78
B.  75
C. None of the choices are correct.

can someone explain me

anonymous · Answer

none of the choices are correct

matt101 · Answer

Say x represents the grade he needs to get. Then we have the following equation:

$$80=\frac{ 78+79+88+x }{ 4 }$$

Once you solve for x, you'll find that x = 75, so the answer is B.

anonymous · Answer

isn't it 83? i got 83

anonymous · Answer

oh sorry, my mistake

anonymous · Answer

It is 75, because when you calculate the mean,( test1+test2+test3+test4(75)/4 tests, you get exactly 80.

anonymous · Answer

thanks guys :D