Question

The average of six numbers is -3.65.If five numbers are each -3.20,what is the sixth number.

Answer 1

we know that the average for six numbers can be writen like:

`A=(x_1+x_2+x_3+x_4+x_5+x_6)/(6)`

So if 5 of them are -3.20 and the average is -3.65 we can replace that values and find the missing one:

`-3.65=(5(-3.20)+x)/(6)`

and we solve for x so:

`\begin{gathered} -3.65\cdot6=-16+x \\ -22+16=x \\ -6=x \end{gathered}`

So the missing value is -6