Question

If $x,y$ and $z$ are three sums of money such that $y$ is the simple interest on $x;z$ is the simple interest on $y$ for the same time and at the same rate of interest, then we have

• A. $x^2=yz$
• B. $y^2=xz$
• C. $z^2=xy$
• D. $xyz=1$

Answer 1

The correct option is B $y^2=xz$

Let the rate of interest=r%
Time t year
$\therefore y=\frac{x\times r\times t}{100}$and
$z=\frac{y\times r\times t}{100}$
$\therefore \frac{y}{z}=\frac{x\times r\times t}{100}\times \frac{100}{y\times r\times t}$
$\frac{y}{z}=\frac{x}{y}$
$xz=y^2$