Q:

What grade does Bob need on his final to pass his math class?

Bob's teacher has a syllabus where the grading breakdown is as follows:

Homework: 10%
Tests (2): 60%
Final Exam: 30%

Bob receives all 10% from the homework
Bob receives 78/100 on Test 1 (78%)
Bob receives 94/100 on Test 2 (94%)

What grade does Bob need on the final exam to get an A in the class (Assuming an A is 90-100%)?

I'm having troubles with Test 1 and Test 2. How do I find out how much percent out of 60 they get?  

A:

These are all weighted grades. 
Homework Average: 100
Test Average: 86
Homework Weighted Average: $100\times0.10=10$
Test Weighted Average: $86\times0.6=51.6$
$\therefore (100\times0.10)+(86\times0.60)+(x\times0.30)=90$
Solve for $x$:
$x=94.7\therefore$ Bob must get at least a 95% on the final exam to get an A in the course

