2 The probability that a phone call will last more than t mi

2. The probability that a phone call will last more than t minutes is (1+t)^-2. Given that a particular phone call has not ended in two minutes, what is the probability it will last more than three minutes?

Solution

Here,

P(T>t) = (1+t)^-2

Thus,

P(t>3|t>2) = P(t>3) / P(t>2)

= [(1+3)^-2]/[(1+2)^-2]

= 9/16 or 0.5625 [ANSWER]