Each question has four choices, then the probability to guess a correct answer is

and the probability to select incorrect choice is

.
You have a 5-question multiple-choice test, then n=5. The <span>probability that you will guess exactly three out of five questions correctly is </span>
<span /><span>
</span><span>

</span>

.
<span />
11/30 - 6/30 - 5/30 = 0
The answer is 0
If 2 sets are disjoint means they have not any common element.
Draw a rectangle & inscribe inside this rectangle 2 circles that do not intersect.
cercle₁ ∩ cercle₂ =Ф.
Their complement would be the part of the rectangle - the 2 circles