Answer:
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 = [tex]x[/tex]
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
[tex]\frac{65 + 73 + 81 + 82 + x}{5}[/tex] = [tex]80[/tex]
[tex]\frac{301 + x}{5} = 80\\[/tex]
Multiplying both side by 5
[tex]301 + x = 400[/tex]
Subtracting both side by 301
[tex]x = 99[/tex]
Therefore, he must score 99 to earn an average test grade of 80 for the five tests.
