Answer:
7.4 cm
Explanation:
Volume of sphere
v = (4/3)πr³
Volume of hemisphere will be half that
v = (2/3)πr³
(2/3)πr³ = 839
multiply both sides by 3/2
πr³ = 1,258.5
Divide both sides by π
r³ = 400.5929917623
Take the cube root of both sides
r = 7.3717022001
Rounded
r = 7.4 cm