Sagot :
If Carol’s final grade is a 91, Carol's lowest test score was 82.
Given;
Average in 9 tests = 90
Average when the lowest score is removed = 91
How to calculate the average?
The average or Mean is calculated as thus;
Average = [tex]\dfrac{\sum x}{n}[/tex]
Where the summation of x is the sum of test scores.
n = number of tests
n = 9 - 1 = 8 and average = 91
91 = [tex]\dfrac{\sum x}{8}[/tex]
[tex]\sum x = 91 \times 8\\\\\sum x = 728[/tex]
Thus, Carol's test score in 8 subjects is 728
Let's consider the 9th subject represent the subject Carol had the least score.
n = 9
Average = 90
Average = 728 + the 9th subject
Multiply both sides by 9
90 x 9 = 728 + the 9th subject
810 = 728 + the 9th subject
Subtract 728 from both sides
810 - 728 = 728- 728 + the 9th subject
82 = the 9th subject
Hence, Carol's lowest test score was 82.
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