A simple qestion

1. Dec 22, 2014

Firedog89

Three of four numbers have a sum of 22. If the average of
the four numbers is 8, what is the fourth number?
A. 4
B. 6
C. 8
D. 10

2. Dec 22, 2014

Maged Saeed

apply the average rule:

the sum of all the numbers / the number of the numbers

you would get only one unknown to find.

3. Dec 22, 2014

Firedog89

I'm not given the other 3 numbers. I think I'm misinterpreting what you are saying sum/amount of numbers or sum/each number totaled up. 22/4=5.5 evenly distributed. I'm also running into an issue also one of the numbers doesn't necessarily have to be 8 the 4 numbers average is 8.

oh wait 3 of 4 numbers have a sum of eight. 6,7,, and 9=22 so the 4th number has to be 8. but 22/3=7.3 I mean visually it makes sense but mathematically I'm not getting the answer.

Last edited: Dec 22, 2014
4. Dec 22, 2014

ehild

The average of the four numbers is 8. What is the sum of the four number?

5. Dec 22, 2014

Firedog89

Would that be (22+x)/4=8 ok I got 10. Thanks. I just had to think a bit more straighter. :)

6. Dec 22, 2014

ehild

Correct! You could have done it without writing an equation.. if the average of N number is A, the sum of them is NA. The average of 4 number is 8, then the sum of them is 32. .But the sum of three of them is 22, and adding the fourth yields 32...

7. Dec 22, 2014

Firedog89

I don't know, I think I work better by writing down equations or just writing everything down.

8. Dec 22, 2014

Staff: Mentor

Please use the template and show some effort.