Question

find the forth proportional of 15 , 6 , 7​

Answer 1

The proportion of four integers a, b, c, and d can be represented as $a:b=c:d$

Here, d is called the fourth proportional to a,b and c.

So it is written as,

$=>\frac{a}{b}=\frac{c}{d}$

The given four values are:

$a=15, b=6, c=7$

Let, $d=x$

By substituting the values, we get:-

$=>\frac{15}{6}=\frac{7}{x}$

By using cross multiplication,

$=>15x=7\times 6$

$=>15x=42$

Divide both the sides by $15$ we get,

$=>x=\frac{42}{15}$

Divide both the numerator and denominator by the GCF to reduce a fraction to its simplest form,

$=>x=\frac{14\times 3}{5\times 3}$

$=>x=\frac{14}{5}$

Hence, the fourth proportional is $\frac{14}{5}.$

Answer 2

Answer :

In the question we are given that numbers 15, 6, 7 are in proportion and we have to find forth proportion.

Let w, x, y, z be the four numbers 15, 6,7 ,? respectively in proportion such that w : x :: y : z

where ' z ' is the forth proportion

we can write  15 : 6 :: 7 : z

as,  $\frac{15}{6} = \frac{7}{z}$

transfering like like terms we get,

⇒   $z = \frac{6 \times 7}{15}$

on simplifying we get,

$z = \frac{14}{5}$

hence 14/5 is the forth proportion.