Answer
0.048 atm.
Work Step by Step
Use equation 10–3b to calculate the change in pressure, then divide by atmospheric pressure.
$$\Delta P = \rho g \Delta h$$
$$\frac{\Delta P}{P_o} = \frac{\rho g \Delta h}{1.013\times10^5\;Pa}$$
$$= \frac{(1.29\;kg/m^3) (9.80\;m/s^2) (380\;m)}{1.013\times10^5\;Pa}=0.048$$