Respuesta :

Answer:

r = 3ft

Step-by-step explanation:

example of a cone-shaped hole is a funnel

V = 1/3 • π • r² • height

21π = 1/3 • π • r²• height

(21)3  = (1/3 • r² • 7)3

63/7 = (r² • 7)/7

√9 = √r²

r = 3