Answer:
-6.2 m/s (downward)
Step-by-step explanation:
The velocity of an object thrown vertically upward is given by:

where:
u is the initial velocity
a = g = -9.8 m/s^2 is the acceleration due to gravity
t is the time
In this problem,
u = 27.1 m/s
t = 3.4 s
So, the velocity after 3.4 s is

and the negative sign means the velocity points downward.