Each test grade in Sara's science class counts for 1/6 of the final grade. The final exam counts for 1/2. Sara's test scores are 72, 84, and 90. Her final exam score is 90.
What is Sara's final grade for the class?
A) 83
B) 86
C) 87
D) 89
(72+84+90)/6 + 90/2 = 86
To calculate Sara's final grade for the class, we need to determine the weighted average of her test scores and final exam score.
First, let's calculate the weighted average of her test scores. Since each test grade counts for 1/6 of the final grade, the total weight of the test scores is (1/6) + (1/6) + (1/6) = 1/2.
To find the weighted average of the test scores, we multiply each test score by its respective weight and then sum them up.
Weighted average of test scores = (72 * 1/2) + (84 * 1/2) + (90 * 1/2) = 36 + 42 + 45 = 123
Next, let's calculate the weighted average of her final exam score. Since the final exam counts for 1/2 of the final grade, the weight of the final exam score is 1/2.
Weighted average of final exam score = 90 * 1/2 = 45
Finally, to find Sara's final grade for the class, we add the weighted average of her test scores and final exam score.
Final grade = 123 + 45 = 168
Since the final grade is out of 200 (1/2 of the final grade), we can find Sara's final grade as a percentage.
Percentage grade = (Final grade / Total possible grade) * 100
= (168 / 200) * 100
= 0.84 * 100
= 84
Therefore, Sara's final grade for the class is 84, which corresponds to option A) in the given choices.