Question

Find the Related Number
Select related number: 21:65::31:? (a) 78 (b) 80 (c) 85 (d) 95

Answer 1

Concept we will using:
(i) If ratios are in proportion then each of the ratios will be equal to each other.
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21:65::31:?

Let the unknown number be x.
'::' represents proportion.

Therefore,
21:65::31:x
⇒21:65=31:x
⇒$\frac{21}{65}= \frac{31}{x}$
Reciprocate both sides:
⇒$\frac{65}{21}= \frac{x}{31}$
Multiply both sides by 31:
⇒$\frac{65}{21}\times 31= x$
⇒95.95=x
⇒x=95.95

The closest number to 95.95 from the given options is 95.

Answer : Option(d): The required number is 95