first convert 4 inches into centimeters.....
10.16cm
then find the volume of the basketball......
V of sphere = 4/3 pi r^3
= 4/3 pi (10.16)^3
= 4393cm^3
you know that cm^3 = mL
so it's 4393mL
now...you solve D=M/V for M by moving the variables around
M = DV
= (13.6 g/mL)(4393mL)
= 59745.97 g of mercury (notice the mL cancelled, leaving only grams)
now convert grams into kilograms......(just move the decimal over 3 to the left or just divide the grams by 1000)
59.74597 kilograms of mercury in the basketball