SOLUTION: the average of four numbers is 638.4 the first four numbers are 216 159.8 and 301.25 Find the fourth number.

Algebra ->  -> SOLUTION: the average of four numbers is 638.4 the first four numbers are 216 159.8 and 301.25 Find the fourth number.      Log On

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 Question 163277: the average of four numbers is 638.4 the first four numbers are 216 159.8 and 301.25 Find the fourth number.Found 2 solutions by edjones, orca:Answer by edjones(7794)   (Show Source): You can put this solution on YOUR website!216+159.8+301.25+x=638.4*4 677.05+x=2553.6 x=2553.6-677.05 x=1876.55 . Ed Answer by orca(409)   (Show Source): You can put this solution on YOUR website!Let the fourth number be x. Then the average of the four number can be expressed as: As the average is 638.4, we have Solving the equation for x, we obtain (multiply both sides by 4)