Area and Volume Quantitative Aptitude Questions Page-3

17) What is the surface area of following figure?
   area trapezium questions
(A) 33 π
(B) 24 π
(C) 25 π
(D) 11 π

View Answer

Answer: Option A

Solution:
S = πrs + πr2
= (π * 3 * 8) + π(3 * 3)
= 24π + 9π = 33π

18) In the figure below, given that AD = 6, CD = 8, AE = x. What is the area of the shaded region?
   area trapezium questions
(A) 28 - 2x
(B) 4(14 - 4x)
(C) 48 - 3x
(D) 7(6 - 3x)

View Answer

Answer: Option C

Explanation:
The difference between the entire rectangle and the white triangle os the shaded area. Thus
(6 * 8 = 48) -
6 * x/2
= 48 - 3x

19) If the radius of the circle is decreased by 20%, than the area
(A) increases by 10%
(B) decreases by 20%
(C) increases by 80%
(D) decreases by 36%

View Answer

Answer: Option D

Solution:
If the radius of a circle is 1, after reducing 20% it becomes 0.8.
Since area = 0.8 * 0.8 = 0.64 => 1 - 0.64 = 0.36%