Question

Find the fourth proportional to $\frac{1}{3},\frac{1}{5},\frac{1}{7}$

Answer 1

Step $1:$ To find the fourth proportional to $\frac{1}{3},\frac{1}{5},\frac{1}{7}$

Let the fourth proportional be $x$

Then $\frac{1}{3},\frac{1}{5},\frac{1}{7}$ and $x$ are in proportion$.$

Product of means $=$ Product of extremes

Step $2:$ Now find the value of x using property of proportion

Product of extremes $=$Product of means

$\frac{1}{3}\times x=\frac{1}{5}\times \frac{1}{7}$

$x=\frac{3}{5\times 7}$

$x=\frac{3}{35}$

Hence, the fourth proportion of $\frac{1}{3},\frac{1}{5},\frac{1}{7}$ is $\frac{3}{35}$