A, B, C and D are four positive numbers such that A is 2/3 times of B, B is 5/6 times of C and C is 3/5 times of D. If the average of 3 times of A and 4 times of D is 900, then the average of all four numbers A, B, C and D is:
A=(2/3)*(5/6)*(3/5)*D
D=3A
Also, average of 3 times A and 4 times D = 900
⇒ 3A + 4D = 1800
Now substituting D=3A in above equation, we get, D + 4D = 1800
D=360
.'. A=360/3=120
B=(3/2)*A=(3/2)*120=180
C=(3/5)*D=(3/5)*360=216
Hence, average of A, B, C & D = (120+180+216+360)/4 = 876/4 = 219
Correct Option 8)