So far, a student has earned the following scores on four 100-point tests this grading period: 65, 73, 81, and 82. What score must the student earn on the fifth and last 100-point test of the grading period to earn an average test grade of 80 for the five tests?

99

Step-by-step explanation:

Given:

A student has earned the following scores on four 100-point tests

65 73 81 82

Average grade of total five test = 80

Question asked:

What score must the student earn on the fifth and last 100-point test of the grading period to earn an average test grade of 80 for the five tests ?

Solution:

Let score earned in fifth test =

By using average formula:

Now, according to the question

Average grade of total five test = 80

Sum of all observation by tatal num. of observation = 80

=

Multiplying both side by 5

Subtracting both side by 301

Therefore, he must score 99 to earn an average test grade of 80 for the five tests.

its a straight line parallel to the time axis