Question

http://prntscr.com/tjwh2o

Answer 1

The relative velocity of rain is:

$$\overrightarrow{v_{rel}} = \overrightarrow{v_{rain}} - \overrightarrow{v_{man}}$$

Using the Pythagorean theorem, obtain:

$$v_{rel} = \sqrt{v_{rain}^2 + v_{man}^2} = \sqrt{10^2 + 3^2} = \sqrt{109} km/h$$

Answer. B) $\sqrt{109} km/h$.