Question

Betty has the following data:

r1391816839
If the mean is 12, which number could r be?

Answer 1

To find a number \( r \) such that when included with the rest of the given data results in a mean of 12, we need to start by understanding the data:

- The provided data is \( r, 1391816839 \).
- The mean is calculated as:

\[
\text{Mean} = \frac{\text{Sum of all values}}{\text{Number of values}}
\]

Here, the sum of all values is \( r + 1391816839 \), and the number of values is 2 (since there are two numbers, \( r \) and \( 1391816839 \)).

Given that the mean is 12, we can set up the equation:

\[
\frac{r + 1391816839}{2} = 12
\]

To eliminate the fraction, multiply both sides by 2:

\[
r + 1391816839 = 24
\]

Next, we solve for \( r \):

\[
r = 24 - 1391816839
\]
\[
r = 24 - 1391816839 = -1391816815
\]

Thus, the value of \( r \) that results in a mean of 12 with the provided data is:

\[
\boxed{-1391816815}
\]