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Find the volume of a sphere whose diameter is 6┬аcm.
42╧А┬аcm3
36╧А┬аcm3
28╧А┬аcm3
48╧А┬аcm3
36╧А┬аcm3
Calculate the radius as half the diameter (r=3), then remember 33=27. Dividing by 3 gives 9, and multiplying by the formula coefficient 4 yields 36╧А.
Diameter of the sphere d = 6 cm.
V=34тАЛ╧Аr3
Calculate the radius as half the diameter (r=3), then remember 33=27. Dividing by 3 gives 9, and multiplying by the formula coefficient 4 yields 36╧А.
Students often use the diameter (6) directly in the radius formula or forget to cube the radius, leading to incorrect calculations like 63 or using d instead of r.
Determine the radius
Since the diameter of the sphere is given as d=6 cm, the radius r is half of the diameter.
r=2dтАЛ=26тАЛ=3┬аcm
Apply volume formula
The volume V of a sphere is calculated using the formula V=34тАЛ╧Аr3.
V=34тАЛ├Ч╧А├Ч(3)3
Final calculation
Substitute r=3 into the equation: V=34тАЛ├Ч╧А├Ч27. Simplifying this gives 4├Ч╧А├Ч9.
V=36╧А┬аcm3
B is correct because calculating the volume with a radius of 3 cm results in exactly 36╧А cm┬│.
This is a standard 3D geometry problem; always convert diameter to radius first to avoid errors in all volume or surface area problems involving spheres or cylinders.