document.write( "Question 765737: Suppose a student has earned the following grades on her first four quizzes: 83, 72, 89, 78. What must she score on her fifth quiz in order to have a mean of 80 on all of her quizzes? \n" ); document.write( "

Algebra.Com's Answer #466369 by MathLover1(20850) $\"\"$ $\"About$

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\n" ); document.write( "\n" ); document.write( "Let $\"x\"$ = score on the 5th quiz to have an $\"80\"$ average\r
\n" ); document.write( "\n" ); document.write( "if first four quizzes are $\"83\"$ , $\"72\"$ , $\"89\"$ , $\"78\"$ , then\r
\n" ); document.write( "\n" ); document.write( " $\"%2883%2B72%2B89%2B78%2Bx%29%2F5=80\"$ .....solve for $\"x\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"83%2B72%2B89%2B78%2Bx=80%2A5\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"322%2Bx=400\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"x=400-322\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"x=78\"$ .... she must score $\"78\"$ to have an average of $\"80\"$ \n" ); document.write( "

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