Volume of a hemisphere is 19404 cu. cm. Its radius is : Choose the most appropriate option:	A) 19 cm	B) 20 cm	C) 21 cm	D) 30 cm	E) none

Rationale: sol . let the radius be r cm . then , 2 / 3 * 22 / 7 * r ³ = 19404 ⇔ r ³ = [ 19404 * 21 / 44 ] = ( 21 ) ³ ⇔ r = 21 cm . answer c
Answer: C