Little chemistry help please?

Question

What is the mass, in kilograms, of an Avogadro's number of Olympic shot-put balls if each one has a mass of 16 lb? How does this compare with the mass of Earth, 5.98 x 10^24kg?

Answer 1

16lbs is a weight, so each ball has a mass of 7.25747792 kg.

7.25747792  x (6.02 x 10^23) = 4.27 x 10^24 kg which is just less than the mass of the Earth.

Answer 2

avogadro's number is 1 mole, which is about 6.022x10^23

so you just multiply 16 by 6.022x10^23 to get lbs, which is=9.6352x10^24

1lb=0.45359237 kilograms, so: 9.6352x10^24 x .45359237=  about 4.370x10^24

it's just about 1.61x10^24 less than the mass of the earth.