Question

The time between arrivals of taxis at a busy intersection is exponentially distributed with a mean of 10 minutes. (a) What is the probability that you wait longer than one hour for a taxi? (b) Suppose that you have already been waiting for one hour for a taxi. What is the probability that one arrives within next 10 minutes? (c) Determine xx such that the probability that you wait more than xx minutes is 0.10. (d) Determine xx such that the probability that you wait less than xx minutes is 0.90. (e) Determine xx such that the probability that you wait less than xx minutes is 0.50

Answer 1

Answer: a)0.025 b)0.63 c)23 d)1.053 e)6.93

Explanation:

E(x)= 10

It is a continuous random variable, so calculating for ✓, we have

10=E(x)1/✓

✓=1/10=0.1

1)P(x>60)=1-F(60)=e^0.1x60=0.0025

2) Employing lack of memory property, we have, P(X<70|X>60)=P(X<10)= F(10)=1-e^-0.1x10= 0.63

3) for 0.1, x= -1/0.1 ln0.1= 23

4) for 0.9, x= -1/0.1 ln 0.9= 1.053

5) for 0.5, x -1/0.1 ln 0.5= 6.3