Q80
V1, V2, V3 and V4 are the volumes of four cubes of side lengths x cm, 2x cm, 3x cm and 4 cm respectively. Some statements regarding these volumes are given below : (i) V1 + V2 + 2V3 < V4 (ii) V1 + 4V2 + V3 < V4 (iii) 2(V1 + V3) + V2 = V4 Which of these statements area correct ?
A.
1 and 2
B.
2 and 3
C.
1 and 3
D.
1, 2 and 3
AnswerAnswer: Option D
Solution
Answer: Option D
Solution:
Clearly, we have :V1 = x3,
V2 = (2x)3 = 8x3
V3 = (3x)3 = 27x3
V4 = (4x)3 = 64x3
(i) V1 + V2 + 2V3
= x3 + 8x3 + 2 × 27x3
= 63x3 < V4
(ii) V1 + 4V2 + V3
= x3 + 4 × 8x3 + 27 x3
= 60x3 < V4
(iii) 2(V1 + V3) + V2
= 2 (x3 + 27x3) + 8x3
= 64x3 = V4