Suppose that the length of a phone call in minutes is an exponential random variable with parameter λ = 1/ 8. if someone arrives immediately ahead of you at a public telephone booth, find the probability that
(a) you will have to wait more than 5 minutes.
(b) you will have to wait between 10 and 20 minutes.
(c) if you have waited for 5 minutes, what is the probability that you will have to wait more than 15 minutes in total?

3

step-by-step explanation:

step-by-step explanation:

let's assume

number of candles set =x

price of of x candles =p(x)

we are given

a candle maker prices one set of scented candles at $10 and sells an average of 200 sets each week

so, we get point as (200,10)

he finds that when he reduces the price by $1, he then sells 50 more candle sets each week

so, we can find slope

now, we can use point slope form of line

now, we can plug values

we can use point

and find b

now, we can plug it back

and we get

now, we can find revenue

we know that

revenue = price*quantity

so, we get