Question 401943
Let X = r.v. representing the number of correct answers.

{{{(1/2)^20*(sum(20Cx, x = 0, 6)) = 0.05766}}}, to 5 decimal places.

{{{(1/2)^20*(sum(20Cx, x = 0, 7)) = 0.13159}}}, to 5 decimal places.

Therefore the lowest passing grade is a 7.