## Essentials of Statistics for the Behavioral Sciences 8th Edition

The new sample mean: $M=7$
$M=\frac{∑X}{N}$ There are 15 scores whose mean is $6$: $6=\frac{X_1+X_2+X_3+X_4+X_5+X_6+X_7+X_8+X_9+X_{10}+X_{11}+X_{12}+X_{13}+X_{14}+X_{15}}{15}$ $X_1+X_2+X_3+X_4+X_5+X_6+X_7+X_8+X_9+X_{10}+X_{11}+X_{12}+X_{13}+X_{14}+X_{15}=6\times15=90$ Now, add the new score: $X_{16}=22$ $M=\frac{∑X}{N}=\frac{X_1+X_2+X_3+X_4+X_5+X_6+X_7+X_8+X_9+X_{10}+X_{11}+X_{12}+X_{13}+X_{14}+X_{15}+X_{16}}{16}$ $M=\frac{90+22}{16}=\frac{112}{16}=7$