If third proportion of 3 and x is 27 and the third proportion of 2 and y is 8, find x : y.
Answer & explanation
Correct answer: option 4
Third proportion of a, b = $\frac{b\; \times\; b}{a}$
Third proportion of 3 and $x$ = $\frac{x\; \times\; x}{3}$ = 27
$x^2$ = 81
$x$ = 9
Third proportion of 2, $y$ = $\frac{y\; \times\; y}{2}$ = 8
$y^2$ = 16
$y$ = 4
Thus, x : y = 9 : 4