The Linear Density of A $48$ M Long Rod Is $\frac{72}{\sqrt{x+1}} \mathrm{~kg} / \mathrm{m}$

Multiple Choice

The linear density of a $48$ m long rod is $\frac{72}{\sqrt{x+1}} \mathrm{~kg} / \mathrm{m}$ where x is measured in meters from one end of the rod. Find the average density of the rod.

A) $\rho_{\text {ave }}=21 \mathrm{~kg} / \mathrm{m}$
B) $\rho_{\text {ave }}=11 \mathrm{~kg} / \mathrm{m}$
C) $\rho_{\text {ave }}=41 \mathrm{~kg} / \mathrm{m}$
D) $\rho_{\text {ave }}=26 \mathrm{~kg} / \mathrm{m}$
E) $\rho_{\text {ave }}=23 \mathrm{~kg} / \mathrm{m}$