SOLUTION: the mean of a set of numbers is 120. if one number is increased by 300, the mean increases to 135. how many numbers are in the set?

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Question 359507: the mean of a set of numbers is 120. if one number is increased by 300, the mean increases to 135. how many numbers are in the set?
Answer by neatmath(302) About Me  (Show Source):
You can put this solution on YOUR website!
You have two unknown numbers in this case.

The mean of a set of numbers is simply the sum total of the set values divided by the number of values in the set.

We will let t be the sum total of the values, and n be the number of values in the set.

So, the mean of a set should be t%2Fn=mean

So, in this case, we are given t%2Fn=120 and %28t%2B300%29%2Fn=135

We just need to solve this system of equations to find t and n, so:

t=120%2An solve for t and plug this into the 2nd equation:

%28120%2An%2B300%29%2Fn=135

120%2An%2B300=135n

300=135n-120n

300=15n

n=20

Thus, there are 20 numbers in the set!

You can then use n=20 to find t, but in this case it is not necessary.

I hope this helps!