SOLUTION: On the first four exams your grades are 77, 94, 59, and 78. you are hoping to earn a C in the course. This will occur if the average of your five exam grades are greater than or eq

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Question 903201: On the first four exams your grades are 77, 94, 59, and 78. you are hoping to earn a C in the course. This will occur if the average of your five exam grades are greater than or equal to 70 and less than 80. What range of grades on the fifth exam will result in learning C?
This is a take home test question and I know the final answer but I want to understand the concept and steps to take for problems like these.
Found 2 solutions by ewatrrr, lwsshak3:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
%2877+%2B+94+%2B+58+%2B+78+%2B+x%29%2F5+%3E=+70
x = 350- (77 + 94 + 58 + 78 ) = 350-307 = 43
%2877+%2B+94+%2B+58+%2B+78+%2B+x%29%2F5+%3C+80
x = 400 - (77 + 94 + 58 + 78 ) = 400 - 307 = 93
43 ≤ x < 93

Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
On the first four exams your grades are 77, 94, 59, and 78. you are hoping to earn a C in the course. This will occur if the average of your five exam grades are greater than or equal to 70 and less than 80. What range of grades on the fifth exam will result in learning C?
***
70%3C-%2877%2B94%2B59%2B78%2Bx%29%2F5%3C80
70%3C-%28%28308%2Bx%29%2F5%29%3C80
lcd:5
350%3C-308%2Bx%3C400
42%3C-%28x%29%3C92
What range of grades on the fifth exam will result in learning C?
[42,92)