Eight identical droplets of water were falling in air with constant velocity $2cm/s.$ The initial acceleration of each droplet was $\text{'}{a}_1\text{'}$  at the time when they start falling. At a time  $\text{'}t\text{'},$ these droplets coalesce to form a big drop due to pressure difference developed and just after the formation of combined drop, its acceleration is found  $\text{'}{a}_2\text{'}.$ The ratio of $\frac{3a_1}{a_2}$  is