Thank you for reporting, we will resolve it shortly
Q.
An observer is approaching a stationary source with a velocity $ \frac{1}{4} ^{th}$ of the velocity of sound. Then the ratio of the apparent frequency to actual frequency of source is
When an observer is moving towards the source apparent frequency
$ n=n\times \left( \frac{{{v}_{1}}+{{v}_{o}}}{v} \right) $
Or $ n=n\times \left( \frac{v+v/4}{v} \right) $
Or $ n=n\times \frac{5}{4} $
Or $ \frac{n}{n}=\frac{5}{4} $