how do i find the value of a missing number when i already have a mean?

Question

i need so much help just help m please!!!

Answer 1

Say you know that your mean involves 7 numbers. Let's say this number is 4.

 

You know the other 6 numbers: 1,2,3,5,6, and 7.

 

Call your missing number X.

 

You then know that:

 

(1 + 2 + 3 + 5 + 6 + 7 + X)/7 = 4

 

So

 

24 + X = 28

 

X = 4

 

Thus, 4 is your missing number.

 

In general:

 

Sum up your known numbers and your unknown number.

 

Divide by the total number of numbers.

 

Set that equal to your known mean.

 

You now have 1 equation, 1 unknown.

 

Hope this helps.