need help with word problems

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boris has scored 90, 94 and 61 on his previous three tests. what score does he need on his next res so that his average (mean) is 76?

Jun 22nd, 2015

Thank you for the opportunity to help you with your question!

Let the score on the last test be x 

The total number of tests after the last test will be 4

mean = (90 +94 +61 +x) /4 = 76     

    (245 + x) /4 = 76

Multiply by 4 on both sides

245 + x = 76 * 4   

245 + x = 304 

subtract 245 from both sides

x = 304 - 245 = 59 

59 is his score on the test if his average score is 76

Please let me know if you need any clarification. I'm always happy to answer your questions.
Jun 22nd, 2015

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