Three of foor numbers have a sum of 22. If the average of the four numbers is 8 what is the fourth number?

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Answer 1 · 2018-05-07T13:57:05

#10#

Let's call the numbers #a#,#b#,#c# and #d#, and let #d# be the unknown number.

We know the following equations hold:

#a+b+c=22#

#\frac{a+b+c+d}{4}=8#

Multiplying by #4# both sides of the second equation, we have

#a+b+c+d = 32#

Solving for #d#:

#d = 32-a-b-c = 32-(a+b+c) = 32-22=10#

since we know from the first equation that #a+b+c=22#