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To pass a course with a B grade, a student must have an average of 80 or greater. A student’s grades on three tests are 73, 86, and 78. Find what score the student must get on the next test to get a B average or better. What grade must the student get? ___ or greater.

 Feb 18, 2021
 #1
avatar+31013 
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(73+86+78 + x) / 4  >= 80

73+86+78 + x >= 320

x >= 83

 Feb 18, 2021
 #2
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To pass a course with a B grade, a student must have an average of 80 or greater. A student’s grades on three tests are 73, 86, and 78. Find what score the student must get on the next test to get a B average or better. What grade must the student get? ___ or greater.    

 

Call the required minimum grade on the next test x  

 

After having taken the next test, i.e., the fourth test, the student wants an average of 80. 

 

the scores he has made .....      73 + 86 + 78 + x 

divided by ....                            ————————        equals 80  

the total number of tests .....                4  

 

this relationship is                      x + 237 / 4  =  80  

 

multiply both sides by 4              x + 237  =  320  

 

subtract 237 from both sides                x  =  83   

 

The student must score 83 on the fourth test to have an average of 80.   

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 Feb 18, 2021
 #3
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oops, I should have used parentheses to comport with PEMDAS. 

 

the line in question should read     "this relationship is   ( x + 237 ) / 4  =  80" 

.

Guest Feb 18, 2021
edited by Guest  Feb 18, 2021

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