Answer
The water in the cloud has a mass between $2\times10^6kg$ to $2\times10^7kg$
Work Step by Step
If we multiply total volume we got in 26a by the density given to us in part c, we get the total mass of water.
$(2\times10^3m^3$ to $2\times10^4m^3)(1000kg/m^3)=2\times10^6kg$ to $2\times10^7kg$
