Given,Radius of the balloon = r = 10 m
Volume of the balloon = 
Thus, the volume of the displaced air is 4190.5 
Given,
Density of air = 1.2 kg 
Then, mass of displaced air = 4190.5  1.2 kg
                                              = 5028.6 kg
Now, mass of the helium (m) inside the balloon is given by,
Now, total mass of the balloon filled with helium = (100 + 1117.5) kg
                                                                             = 1217.5 kg
Hence, pay load = (5028.6 – 1217.5) kg
                           = 3811.1 kg
Hence, the pay load of the balloon is 3811.1 kg.