Mensuration Practice Test 4

Question : 3 of 40

Marks: +1, -0

A right circular cylinder and right cone have equal bases and equal heights. If their curved surface areas are in the ratio of 8 : 5, determine the ratio of the radius of the base to the height of either of them.

1 : 2
3 : 4
2 : 3
4 : 5

Validate

Solution:

Ratio =

{\right \circular \cylinder }/{\right \circular \cone}

8/5

{2πrh}/{πrl}

8/5

{2πrh}/{ πr(√{r^2+h^2})}

8/5

{2h}/√{r^2+h^2}

8/5

10h =

8√{r^2+h^2}

Squaring both sides,

100h^2

64r^2+64h^2

100h^2-64h^2

64r^2

36h^2

64r^2

{36}/{64}

r^2/h^2

√{{36}/{64}}

r/h

r : h, 6 : 8
3 : 4

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