Question

A cylindrical pencil of diameter 1.2 cm has one of its end sharpened into a conical shape of height 1.4 cm. The volume of the material removed is

A 1.056 cm3 Correct Answer Incorrect Answer
B 4.224 cm3 Correct Answer Incorrect Answer
C 10.56 cm3 Correct Answer Incorrect Answer
D 42.24 cm3 Correct Answer Incorrect Answer

Solution

= πr2h – 1/3 πr2 h = 2/3 πr2   {r = (1.2/2) = 0.6, h = 1.4} 2/3 × 22/7 × 0.62 × 1.4 = 2 × 22 × 0.2 × 0.2 × 0.6 = 1.056 cm3

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