4 It is known that in an electronic circuit, the number of electrons passing per nanosecond can be modelled by a Poisson distribution. In a particular electronic circuit, the mean number of electrons passing per nanosecond is 12 .

1. 1. Determine the probability that there are more than 15 electrons passing in a randomly selected nanosecond.
   2. Determine the probability that there are fewer than 50 electrons passing in a randomly selected period of 5 nanoseconds.
2. Explain what you can deduce about the electrons passing in the circuit from the fact that a Poisson distribution is a suitable model.