Question

the mean of four numbers is 7. three of the numbers are 5, 7, and 7. what is the fourth number? Explain

Answer 1

Hello!

`\sf the~ fourth ~number ~=~ x\\\\\\\Large \underline{\textbf{Equation:}}\\\\\\(5+7+7+x)/(4) = 7\\\\\\\Large \underline{\textbf{Solve the equation:}}\\\\\\(5+7+7+x)/(4) = 7\\\\\\(19+x)/(4) = 7\\\\\\(19+x)/(4) *~4~= ~7~*~4\\\\\\19+x~= ~28\\\\\\x = 28 - 19\\\\\boxed{ \textbf{\sf x = 9}}`

The fourth number is 9.