There are several many equations that are available to relate the distance, 
speed, and time of a body moving vertically in gravity.  Happily, the only one 
I can always remember without looking it up happens to be the right one to 
use for this question !
             Distance  =  (1/2) x (gravity) x (time)²
                   3.8 m  =  (1/2) x (9.8 m/s²) x (time)²
Divide each side
by 4.9 m/s² :
                   (3.8 m) / (4.9 m/sec²)  =  (time)²
                     0.7755  sec²  =  time²
Square root
of each side:
                        0.88 second  =  time