The time between customer arrivals is called inter-arrival time. According to Queueing Notation, the inter-arrival time can be model based on difference probability distribution. The probability distribution by which the inter-arrival time can be modeled include:
We need to multiply 0.98 by 2 which is 1.96 now we need to divide 0.98 by two which is 0.49, so add those together and you have 2.45. Hope this helps :)