We now need to find a value for n such that P(r 2 3) 2 0.84. Clearly, if we wish to find at least three extroverted professors we will need to interview at least three professors. So, we know that, minimally, n must be at least 3. Since n must be at least 3, suppose we start by trying n = 3, where exactly three professors are interviewed. Here, P(r 2 3) can be calculated using the following formula. P ( r 2 3 ) = P 0 x Submit Skip (you cannot come back)