College Physics (4th Edition)

The fractional change of the brain's volume is an increase of $3.33\times 10^{-5}$
We can find the pressure difference $\Delta P$: $\Delta P = (31~kPa)-(101~kPa)$ $\Delta P = -70~kPa$ We can find the fraction that the volume changes: $\frac{\Delta V}{V_0} = -\frac{1}{B}~\Delta P$ $\frac{\Delta V}{V_0} = -\left(\frac{1}{2.1\times 10^9~Pa}\right)~(-7.0\times 10^4~Pa)$ $\frac{\Delta V}{V_0} = 3.33\times 10^{-5}$ The fractional change of the brain's volume is an increase of $3.33\times 10^{-5}$.