Question

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.

Answer 1

Hint: In the above question we will use the formula of curved surface area which is given below, Curved surface area of the hemisphere is = $2\pi {{r}^{2}}$ where r is the radius of the hemisphere.

Complete step-by-step answer:
In the above question, the thickness and the inner radius of the bowl are given but we have to find the outer curved surface area so we will have to find the outer radius of the bowl which is equal to the summation of inner diameter and the thickness. Let us consider the figure first. The figure has all the markings of the dimensions, i.e. the inner radius of the bowl and also the thickness of the bowl.

Hence, the outer circle radius = \[0.25cm+5cm=5.25cm\].
Now, the outer curved surface area = \[2\pi {{r}^{2}}=(2\times \pi \times 5.25\times 5.25)c{{m}^{2}}=173.25c{{m}^{2}}\]
Therefore, the outer curved surface area of the bowl is 173.25\[c{{m}^{2}}\].

Note: Be careful while doing calculation as there is a chance that you might make a mistake during the calculation and you will get the incorrect answer. Remember all formulae related to hemisphere because it will help you a lot in this type of question. Remember in the above question we will have to calculate the outer surface area of the given bowl so we will have to use the outer radius of the bowl in spite of inner radius.