Bunuel
What is the area of the larger of two circular regions, D and E?
(1) The smaller circular region has a circumference one-fourth that of the larger circular region.
(2) The radius of D and E together is equal to 25.
Asked: What is the area of the larger of two circular regions, D and E?
Let the radius of larger circular region be R and radius of smaller circular region be r.
(1) The smaller circular region has a circumference one-fourth that of the larger circular region.
\(2\pi r = 1/4 2 \pi R\)
r = R/4
Since absolute values are unknown
NOT SUFFICIENT
(2) The radius of D and E together is equal to 25.
r + R = 25
R = 25 - r
Since r is unknown
NOT SUFFICIENT
(1) + (2)
(1) The smaller circular region has a circumference one-fourth that of the larger circular region.
r = R/4
(2) The radius of D and E together is equal to 25.
r + R = 25
R + R/4 = 25
R = 20
Area of larger circular region = \(\pi R^2 = \pi 20^2 = 400 \pi\)
SUFFICIENT
IMO C