3. The average time between telephone calls to a company switchboard is u = 2.5 minutes. Calculate the probability that the time between 2 consecutive calls is less than 3 minutes, (remember that waiting time for an event can be modelled using exponential probability distribution). (2 marks) 4. In a city, 48% of the population would like the current mayor to win the next municipal election. A simple random sample of 500 is taken. Find the probability that at least 260 favor the current mayor