Question

Marta hopes to have a test average of at least 90 by the end of the marking period. Her grades on the first four tests have been 86, 84, 97 and 89. What is the lowest grade she can receive on her fifth and final test and still have a test average of 90 or higher?

Answer 1

Answer:

 Marta need to score at least 94 to receive an average of 90 or higher considering all five tests.

Explanation:

 Marks received by Marta in four tests =  86, 84, 97 and 89

 Let mark received in fifth test be x

 We have average of five test is more than or equal to 90

 So we have

    $\frac{86+84+97+89+x}{5} \geq 90\\ \\ 86+84+97+89+x\geq 450\\ \\ x\geq 94$

 So Marta need to score at least 94 to receive an average of 90 or higher considering all five tests.