The density of lead is 11.34 g/cm3 and the density of aluminum is 2.69 g/cm3. Find the radius of lead and aluminum spheres each having a mass of 70 kg. (Round your answers to two decimal places.)

Iam lost on everything I got this far
p(4/3)πr^3=m
r-(3m/(4πp))^1/3

1 answer

Well, 70 kg = 70,000 g
so the volume of the lead ball = 70000/11.34 cm^3 = 6172.8395 cm^3
the volume of the aluminium ball = 70000/2.69 cm^3 = 26022.305 cm^3

Now we'll use our sphere formula:
for the lead,
(4/3)πr^3 = 6172.8395
r^3 = 1473.65...
r = (1473.65...)^(1/3) = appr 11.38 cm

for the aluminum,
(4/3)πr^3 = 26022.305
r^3 = 6212.367...
r = 18.38 cm