Answer:
[tex]M_1 = 317.7 kg[/tex]
Explanation:
Mass of the helium gas filled inside the volume of balloon is given as
[tex]m = \rho V[/tex]
[tex]m = 0.179(\frac{4}{3}\pi R^3)[/tex]
[tex]m = 0.179(\frac{4}{3}\pi 6.55^3)[/tex]
[tex]m = 210.7 kg[/tex]
now total mass of balloon + helium inside balloon is given as
[tex]M = 210.7 + 990[/tex]
[tex]M = 1200.7 kg[/tex]
now we know that total weight of balloon + cargo = buoyancy force on the balloon
so we will have
[tex](M + M_1)g = \rho_{air} V g[/tex]
[tex](1200.7 + M_1) = (\frac{4}{3}\pi 6.55^3) (1.29)[/tex]
[tex]1200.7 + M_1 = 1518.4[/tex]
[tex]M_1 = 317.7 kg[/tex]