For (a) and (b)
The uniform distribution has the following properties:
The mean of the distribution is μ = (a + b) / 2.
The standard deviation of the distribution is s = .
It is written in any textbook on probability.
Here a = 0; b= 8 minutes. So,
μ = = 4 minutes.
s = = = = 2.3094 minutes.
(c) P = = = = 0.25.
(d) P = = = 0.025974. Round as you want.
(e) This question is posed INCORRECTLY.
It should ask about a bus, not about a train. Train is irrelevant.