Question 639753: The average of 5 numbers is 20. If one of the
numbers is 18, then what is the sum of the
other four numbers?
a.2
b.20.5
c.82
d.90
e.100
Answer by neatmath(302)   (Show Source):
You can put this solution on YOUR website!
Average, or mean, is just the total sum of the numbers, divided by the actual count of the numbers.
So here we have an average of 20, given that we have 5 numbers.
We just need to work backwards then.
If our average is 20, and there are 5 numbers, then our total sum of the numbers is just 5*20, or 100.
Since we know one of our numbers is 18,
the sum of the other 4 numbers is simply 100-18, or 82 (which is choice C).
I hope this helps! :)
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