Question

Determine if the following is in proportion.

$5,9,15,27$

Answer 1

If $a,b,c,d$are in proportion then,

$a\times d=b\times c$

So, here we have $5,9,15,27$

in which

$a=5,b=9,c=15,d=27$

now, $5\times 27=135$

and, $9\times 15=135$

Hence $a\times d=b\times c$

So, $5,9,15,27$ are in proportion.