SSC CHSL 10-Jan-2017 Shift 1 Paper

Three numbers a,b,c are in proportion iff b2=ac where b is the mean proportion and c is the third proportion Mean proportion of two numbers x and y = 8
⇒ xy=(8)2=64 ------(i)
Third proportion = 512
⇒ y2=x×512 ------(ii)
Substituting value of from equation(i) in equation(ii), we get :
⇒ y2=

64

y

×512
⇒ y3=(2)6×512
⇒ y=(2)

15

3

=25=32
Substituting it in equation(i), ⇒ x=

64

32

=2