Question

The mean of four numbers is 85. The four numbers are 86, 83, 81, and .
a) Write an equation to show this information
b) Solve the equation for .

Answer 1

Answer:

90

Step-by-step explanation:

a)

Since, to find the average of a set of numbers, you need to add them all together and divide by the amount of numbers:

$\dfrac{86+83+81+x}{4}=85$

b)

Multiply both sides by 4:

$86+83+81+x=340\\x=90$

Hope this helps!