Question

Choose the appropriate number for fourth place: $13:91::131:$?

Answer 1

Solve for the required value:

Let the value in fourth place be $x$

$13:91::131:x$ implies that the relation between $13$ and $91$ is the same as that of $131$ and $x$

$\Rightarrow$ $\frac{13}{91}=\frac{131}{x}$

On cross multiplication we get

$\Rightarrow$$13x=91\times 131$

$\Rightarrow$ $x=7\times 131$

$\Rightarrow$ $x=917$

Hence, the number in the fourth place is $917$.