SSC CHSL 8-Jan-2017 Shift 3 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 = 16
⇒xy=(16)2=256 -----(i)
Third proportion = 128
⇒ y2=x×128 ------(ii)
Substituting value of from equation(i) in equation(ii), we get :
⇒ y2=

256

y

×128
⇒ y3=(2)8×(2)7=(2)8+7
⇒y=(2)

15

3

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

256

32

=8