A spherical balloon has a radius of 6.95

**Answer 1**

The weight of the air displaced = m*g = Density*Volume*g

m*g = D*V*g = 1.29*4*π*6.95³/3 *9.81 = 17,795N

The weight of the helium =

m*g = D*V*g = 0.179*4*π*6.95³/3 *9.81 = 2,469N

2,469 + 9.81*920 = 11,495

[17,795-11,495]/9.81 = 642kg

**Answer 2**

The volume of the balloon is

Sphere V = ⁴/₃πr³ = ⁴/₃π7³ = 1437 m³

(I’ll round, you can correct)

buoyancy is diff between weight of air and of helium

1.29 kg/m³ – 0.179 kg/m³ = 1.11 kg/m³

1.11 kg/m³ x 1437 m³ = 1595 kg

1595–920 = 675 kg