I need help with the word problem

Question

Suppose that you are taking a course that has 4 tests. The first three tests are each worth 20% of your final grade, and the fourth test is worth 40% of the final grade. To get a B in the course, you must have an average of at least 80 percent on the 4 tests. Your scores on the first 3 tests were
60.5
60.5 %,
79
79 %, and
93
93 %. What is the minimum score you need on the fourth test to get a B for the course?

Answer 1

Let x = the minimum score required to get an average of 80

 

Set up a combination of test scores, weighted by how much each test is worth:

 

80 = 0.20(60.5) + 0.20(79) + 0.20(93) + 0.40x

 

x = 83.75

 

You need at least 83.75% on the test that is worth 40% of the grade.

Answer 2

Basically the last test counts twice

 

(60.5 + 79 + 93 + 2x)/5 ≥ 80

 

232.5 + 2x ≥ 400

 

2x ≥ 167.5

 

x ≥ 83.75

 

I don't know if you can get partial points so I would go for at least an 84%