The average of integers a and b is 12. If c = 3, what is the average of integers a, b, and c?

Question

anonymous · Answer

Lets make up a question real quick.  if a=16 and b= 8, do you know how to average those two?

anonymous · Answer

divide

anonymous · Answer

not quite.
we would want to sum, a and b.  Then we need to divide how many items we have, which is two.
So here, we would need to do this:
$${a+b \over 2}$$
Does that make sense?

anonymous · Answer

not quite so will i go 12 + 3 then

anonymous · Answer

Nope.  If 12 was the avg of two items, we would need to "undo" the avg.  Do you have an idea on how we'd do that?

anonymous · Answer

no can you explain it

anonymous · Answer

i got 9

anonymous · Answer

well if our avg is 12 and it's the avg of two items then to undo the avg we will want to multiply it by two.  That way we get what the sum of a+b was.  Does that make sense?

anonymous · Answer

YEAH buddy!  it is 9.