What will my final grade be?

Question

So I took my first final and I only finished half. My final is worth 20% of my grade. My current grade is a 89%. Assuming I get a 50% on my final, how much will it affect my grade.

Answer 1

.8(89) + .2(50 =71.2 + 10 = 81.2. The 50 will drop your grade by 6.8 percent. You'll go from B+ to B-

If they just give letter grades without plus or minuses, then you'll stay the same, grade of B