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Find the volume of a sphere whose radius is 7 cm. (Use pi = 22/7)
1437.33 cm³
1386 cm³
1232 cm³
1540 cm³
1437.33 cm³
Since the volume formula includes r3, and r=7, the volume must be a multiple of 72=49. Check divisibility of options by 49 or look for a value approximately equal to 4.18×343≈1433.
Radius of the sphere r = 7 cm, value of pi = 22/7.
V=34πr3
Since the volume formula includes r3, and r=7, the volume must be a multiple of 72=49. Check divisibility of options by 49 or look for a value approximately equal to 4.18×343≈1433.
Many students confuse the volume formula of a sphere (34πr3) with the surface area formula of a sphere (4πr2).
Identify given parameters
We are given the radius r=7 cm and the constant π=722.
r=7,π=722
Apply volume formula
Substitute the values into the sphere volume formula: V=34πr3.
V=34×722×73
Simplify calculation
Simplify the expression by canceling one 7 from the denominator: V=34×22×72=34×22×49.
V=388×49=34312
Final division
Calculate the final quotient: 4312÷3=1437.333... cm3.
V≈1437.33 cm3
A is correct because the calculation of 34312 results in approximately 1437.33 cm3.
Remember that if the problem asked for the surface area (4πr2), the answer would be 4×722×49=616 cm2. Surface area is in square units, while volume is in cubic units.