Question : A solid right circular cylinder and solid hemisphere stand on equal bases and have the same height. The ratio of their whole surface area is:
Option 1: 3 : 2
Option 2: 3 : 4
Option 3: 4 : 3
Option 4: 2 : 3
Correct Answer: 4 : 3
Solution : Let the radius of the base as $r$ and the height of the cylinder and hemisphere as $h$. The total surface area of a right circular cylinder $=2\pi r(r+h)$ The total surface area of a hemisphere $=3\pi r^{2}$ Given that the cylinder and hemisphere stand on equal bases and have the same height, such that $r = h$. Substituting $r = h$ into the formulas, The total surface area of the cylinder = $2\pi r(r+r) = 4\pi r^{2}$ The total surface area of the hemisphere = $3\pi r^{2}$ The ratio of their whole surface area $=4\pi r^{2}: 3\pi r^{2} = 4:3$ Hence, the correct answer is 4 : 3.
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Question : A sphere and another solid hemisphere have the same surface area. The ratio of their volumes is:
Option 1: $2 \sqrt{3}: 8$
Option 2: $3 \sqrt{3}: 8$
Option 3: $3 \sqrt{3}: 4$
Option 4: $\sqrt{3}: 4$
Question : The radius of the ends of a frustum of a solid right-circular cone 45 cm high is 28 cm and 7 cm. If this frustum is melted and reconstructed into a solid right circular cylinder whose radius of base and height are in the ratio 3: 5, find the curved surface area (in ${cm}^2$ ) of this cylinder. [Use $\pi=\frac{22}{7}$.]
Option 1: 4580
Option 2: 4610
Option 3: 4640
Option 4: 4620
Question : The curved surface area and circumference at the base of a solid right circular cylinder are 2200 cm2 and 110 cm, respectively. Find the height of the cylinder.
Option 1: 24 cm
Option 2: 22 cm
Option 3: 20 cm
Option 4: 18 cm
Question : The total surface area of a right circular cylinder is 1848 cm2. The ratio of its total surface area to the curved surface area is 3 : 1. The volume of the cylinder is: (Take $\pi=\frac{22}{7}$)
Option 1: 4312 cm3
Option 2: 3696 cm3
Option 3: 4002 cm3
Option 4: 4851 cm3
Question : The height and curved surface area of a right circular cylinder are $7~\text{cm}$ and $70\pi~\text{cm}^2$. Its total surface area is:
Option 1: $140 \pi~\text{cm}^2$
Option 2: $150 \pi~\text{cm}^2$
Option 3: $180 \pi~\text{cm}^2$
Option 4: $120 \pi~\text{cm}^2$
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