SOLUTION: Sam must have an average of 70 or more in his summer course to obtain a grade of C. Her first three test grades were 75,63, and 68. Write an inequality representing the score that

Algebra ->  Equations -> SOLUTION: Sam must have an average of 70 or more in his summer course to obtain a grade of C. Her first three test grades were 75,63, and 68. Write an inequality representing the score that       Log On


   

Question 114871: Sam must have an average of 70 or more in his summer course to obtain a grade of C. Her first three test grades were 75,63, and 68. Write an inequality representing the score that Sam must get on the last test to get a C.
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!
The average for the four tests, the three for which you have scores plus the last test that hasn't been taken yet, is the sum of those four scores divided by four.

%2875%2B63%2B68%2Bx%29%2F4, and this average must be greater than or equal to 70, so %2875%2B63%2B68%2Bx%29%2F4%3E=70

Multiply both sides by 4:
75%2B63%2B68%2Bx%3E=280

Simplify:
206%2Bx%3E=280
x%3E=280-206=74, so Sam needs to get at least a 74 on his/her final to make a C in the course.

Super-Double-Plus-Extra-Credit: If an 80 average were needed for a B, and the maximum possible score on the final is 100, can Sam earn a B? Why or why not?