CTET 2 Math and Science 23 Dec 2021 Paper

Question : 47 of 151

Marks: +1, -0

The radii of the bases of two right circular cylinders are in the ratio of 3 : 4 and their heights are in the ratio of 4 : 5, The ratio of their curved surface areas is

4 : 9
3 : 5
5 : 12
7 : 12

Validate

Solution:

Let assume that

r_1=3 r

{\r}_2=4 {\r}

{\h}_1=4 {\h}

{\h}_2=5 {\h}

The curved surface of cylinder 1 : The curved surface of cylinder 2

⇒ 2 π(3 {\r})(4 {\h}): 2 π(4 {\r})(5 {\h})

⇒ 3: 5

∴

The ratio of curved surface areas is

3: 5

The correct option is 2 i.e.

3: 5

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