Students who are participating in dance from class VII are what percent more or less than students who are participating is play from class IX.

Students participating in dance from Class VII

$= frac{{10}}{{100}} imes 400 = 40$

Students participating in play from class IX

$= frac{{12}}{{100}} imes 250 = 30$

Required percentage

$= frac{{10}}{{30}} imes 100 = frac{{100}}{3}{ m{\% }} = 33frac{1}{3}{ m{\% }}$