The diameter of the sphere is 7.5 cm, therefore its volume is
V = [(4π)/3]*(7.5/2 cm)³ = 220.8932 cm³
The density of the lead ball is 11.34 g/cm³, therefore its mass is
m = (220.8932 cm³)*(11.34 g/cm³) = 2.5049 x 10³ g = 2.5048 kg
Answer: 2.5 kg (nearest tenth)