103k views
5 votes
On four exams, Wallace’s grades were 79,93,91, and 68. What grade must he obtain on his fifth exam to have an 80 average?

User Hounded
by
8.3k points

2 Answers

3 votes
(79 + 93 + 91 + 68 + x) / 5 = 80
(331 + x) / 5 = 80.....multiply both sides by 5
331 + x = 80 * 5
331 + x = 400
x = 400 - 331
x = 69 <=== he would have to make at least a 69
User T Davey
by
8.7k points
3 votes

(79 + 93 + 91 + 68 + x) / 5 = 80

Simplify

(331 + x)/5 = 80

Multiply 5 to both sides to isolate the x.

331 + x = 400

Isolate the x. Subtract 331 from both sides

x + 331 (-331) = 400 (-331)

x = 69

69 is your answer

hope this helps

User TrN
by
8.1k points

Related questions

1 answer
5 votes
75.5k views
1 answer
0 votes
59.3k views
1 answer
4 votes
85.0k views