Question

Sum of volume of cylinder (S) and volume of cone (C) is 4380n cm2 & height of both, cylinder and cone is same i.e, 20 cm. If radius of cone is 15 cm then find the ratio of radius of S to radius of C?
A. `1:2`
B. `3:4`
C. `2:5`
D. `4:5`

Answer 1

Correct Answer - D
Volume of cylinder (S) `=pir^2h`
`(rto"radius")`
`(hto"height")`
Volume of cone (C ) `=1/3piR^2H`
`(R to"radius")`
`(H to "height")` ltbRgt `h=H=20 cm`
ATQ,
`pir^2h+1/3piR^2h=4380pi`
`pixx20[r^2+1/3xx15xx15]=4380 pi`
`r=12`
`:.r/R=12/15=4:5`