Call [tex]n[/tex] the number of responses.
[tex]P(n \ \textless \ = 2) = P(n=0) + P(n=1) + P(n=2)[/tex]
Each of those probabilities will be the frequency of occurrence of the particular event. We get zero responses 20 out of 200 times, 1 response 30 out of 200, and 2 responses 56 out of 200 times. So
[tex]P(n \le 2) = \dfrac{20}{200} + \dfrac{30}{200} + \dfrac{56}{200} = \dfrac{20+30+56}{200} = \dfrac{106}{200} = 53\%[/tex]
We see we could have just said 20+30+56=106 of the 200 editorials got zero, one or two responses, so the probability is 106/200.
