To solve this problem we will apply the concept of potential difference defined as the product between the electric field and distance, that is
[tex]V = E \Delta l[/tex]
Here,
E = Electric Field
[tex]\Delta l[/tex] = Length
Our values are,
[tex]E = 3MV/m[/tex]
[tex]l = 1.98*10^{-3} m[/tex]
Replacing,
[tex]V = (3 MV/m)( 1.98*10^{-3} m)[/tex]
[tex]V= 5.94*10^{-3} MV[/tex]
[tex]V = 5940V[/tex]
Therefore the difference potential between you and your friend just before the spark is 5940V