Question 329074: My test scores are75,90,77,88, out of 100. What should my fifth grade so that the average is at least 83?
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! Your total score now is 75 + 90 + 77 + 88 = 330
You have 4 scores.
Add one more score and you'll have 5 scores.
Divide that by 5 and you'll get the new average.
You want the new average to be >= 83.
Let x be the fifth score.
Your formula is (330 + x) / 5 >= 83
This will give you 5 scores that, divided by 5, will give you an average that is greater than or equal to 83.
Multiply both sides of that equation by 5 to get:
330 + x >= 83 * 5 which becomes:
330 + x >= 415
Subtract 330 from both sides of the equation to get:
x >= 415 - 330 which becomes:
x >= 85.
You need to get 85 or more to have an overall average of 83.
Your old total is 330.
Add 85 to it to get a new total of 415.
Divide 415 by 5 and you get an average of 85.
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