Firstly we will determine the average or the mean of the objects density:
[tex]\begin{gathered} Mean=\frac{1.3g•mL^{-1}+1.25g•mL^{-1}+1.17g•mL^{-1}+1.22g•mL^{-1}}{4} \\ Mean=\frac{4.94g•mL^{-1}}{4} \\ Mean=1.235 \end{gathered}[/tex]Now we will calculate the deviation. The deviation is how much is trial is different from the average. We take the absolute value so the answers can be positive:
[tex]\begin{gathered} Trial\text{ }1:|1.3-1.235|=0.065 \\ Trial\text{ }2:|1.25-1.235|=0.015 \\ Trial\text{ }3:|1.17-1.235|=0.065 \\ Trial\text{ }4:|1.22-1.235|=0.015 \end{gathered}[/tex]We will determine the average of the deviation:
[tex]\begin{gathered} Deviation\text{ }mean=\frac{0.065+0.015+0.065+0.015}{4} \\ Deviation\text{ }mean=0.04 \end{gathered}[/tex]To determine the percent deviation we:
[tex]\begin{gathered} \%\text{ }deviation=\frac{mean\text{ }deviation}{mean}\times100 \\ \\ \%\text{ }deviation=\frac{0.04}{1.235}\times100 \\ \\ \%\text{ }deviation=3.24\% \end{gathered}[/tex]Answer: The percent deviation from the mean is 3.24%,