Projectiles A and B are thrown at angles of \( 45^\circ \) and \( 60^\circ \) with vertical respectively from top of a \( 400 \, \text{m} \) high tower. If their range and times of flight are same, the ratio of their speeds of projection \( v_A : v_B \) is:
[Take \( g = 10 \, \text{m s}^{-2} \) ]