Multiple choice

A hemispherical bowl is made of steel, $0.25cm$ thick. The inner radius of the bowl is $5cm$. Find the outer curved surface area of the bowl.

  1. $173\ {cm}^{2}$
  2. $133\ {cm}^{2}$
  3. $143\ {cm}^{2}$
  4. $273\ {cm}^{2}$
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A Correct answer
Explanation

Inner radius = 5 cm, thickness = 0.25 cm, so outer radius R = 5.25 cm. The outer curved surface area of a hemisphere is 2 * pi * R^2. 2 * 3.14 * (5.25)^2 = 2 * 3.14 * 27.5625 = 173.29, which rounds to 173.

AI explanation

The outer radius of the bowl is the inner radius plus the thickness, giving 5 plus 0.25 equals 5.25 centimeters. The outer curved surface area of a hemisphere is 2 times pi times the square of its radius, so we calculate 2 multiplied by 22 over 7 and 5.25 squared. This gives 44 over 7 times 27.5625, which equals 173.25 square centimeters, rounding to 173 square centimeters.

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