Question

What grade must I get to have an average of 89%. my grades are 83% and 85%

Answer 1

• 99%

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Let the required grade be x.

Then the average for three grades is:

• (83 + 85 + x)/3 = 89

Multiply both sides by 3:

• 168 + x = 89*3

Subtract 168 from bot sides:

• 168 + x = 267
• x = 267 - 168
• x = 99

You must get a 99%.