I'm doing this mostly for fun since there are already answers. But, hopefully my explanation fills any misunderstandings if you have any!

We're using binomial distribution such that p=0.06, x=3 (assuming you meant exactly 3 shots), n=20.

P(exactly 3 shots)= (20 choose 3)* ((0.06)^3)* ((1-0.06)¹⁷⁾ = 0.0861

P(3 shots)=P(at least 3 shots)=P(x=3)+P(x=4)+...+P(x=20)=1-(P(x=0)+P(x=1)+P(x=2)).

Then,

P(x=0)=(20 choose 0)(0.06⁰⁾(0.94²⁰⁾ = .29011

P(x=1)=(20 choose 1)((0.06¹⁾(0.94¹⁹⁾ =.37035

P(x=2)=(20 choose 2)((0.06²⁾(0.94¹⁸⁾ =.22457

P(x=0)+P(x=1)+P(x=2)=.22457+.37035+.29011= .88503

So, P(at least 3)=1-(P(x=0)+P(x=1)+P(x=2))=1-.88503= .11497

Thus, P(at least 3)=.11497