So far this year Nick has scored a 75, 81, 88 and 92 on four of his math tests. Each test is worth a maximum of 100 points.

To earn a B this year, Nick needs a test average of 80 or better.

Write the inequality that represents this scenario. Let t equal Nick's grade on the fifth and the last test.

___+ t ≥ ___

4 answers

336 + t ≥ 400
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t1 = 75 = results of the first test

t2 = 81 = results of the secondt test

t3 = 88 = results of the third test

t4 = 92 = results of the fourth test

t = results of the fifth test

average of 5 test

a = ( t1 + t2 + t3 + t4 + t ) / 5

Nick needs a test average of 80 or better mean:

( t1 + t2 + t3 + t4 + t ) / 5 ≥ 80

( 75 + 81 + 88 + 92 + t ) / 5 ≥ 80

( 336 + x ) / 5 ≥ 80 Multiply both sides by 5

336 + t ≥ 80 * 5

336 + t ≥ 400 Subtract 336 to both sides

336 + t - 336 ≥ 400 - 336

t ≥ 64

Proof:

( t1 + t2 + t3 + t4 + t ) / 5
=

( 75 + 81 + 88 + 92 + 64 ) / 5 =

400 / 5 = 80