The ratio of rms speed of an ideal gas molecules at pressure p to that at pressure 2p at const volume is

According to the question,In the first condition,  p = 13ρvrms2                     …(i)In the second condition,                                2p=13ρvrms'                       …(ii)On dividing Eq. (i) by Eq. (ii), we get                        vrms2vrms'2=12⇒vrmsvrms'=12