Question

Please help por favor!
To pass a course with a C ​grade, a student must have an average of 70 or greater. A​ student's grades on three tests are 75​, 74​, and 67. Find what score the student must get on the next test to get a C average or better.

Answer 1

Here's what we know so far:
The average of all the tests must be 70. Since we're given 3 tests, and it says what must the grade on the next test be, that means we have 4 tests total. Therefore:

\[\huge 70=\frac{75+74+67+x}{4}\]

Solve for x

Answer 2

So would I need to add the 3 numbers together first?

Answer 3

You can! Or you can multiply both sides by 4 first and then proceed from there.

Answer 4

If you want to add the 3 numbers first, then you get\[\huge 70=\frac{216+x}{4}\]

Answer 5

Ok, so now I divide by 4?