Given
Exponential probability distribution

Find
a) what is the mean time between phone calls?
b) what is probability of 30 seconds or less between phone calls?
c) what is probability of 1 minute or less between phone calls?
d) what is probability of 5 or more minutes without a phone call?
Step-by-step explanation
given

formula for the probability exponential distribution is given by
![\begin{gathered} P(x\leq a)=1-e^{-(a)/(\mu)} \\ P(aa) the mean is the reciprocal of the constant , so[tex]\mu=(1)/(0.50)=2]()
b) probability of 30 seconds or less between phone calls is

c) probability of 1 minute or less between phone calls

d)
probability of 5 or more minutes without a phone call

Final Answer
Therefore ,
a) 2 minutes
b) 0.2212
c) 0.3935
d) 0.0821