Answer:
The  value is  [tex]\Delta t  =  0.01 \ s[/tex]
Explanation:
From the question we are told that
  The time of flight is  [tex]T  =  0.02 \  s[/tex]
Given that the value of the time of flight is in three decimal place then the error quote is
   [tex]\Delta t  =  0.01 \ s[/tex]