Advertisements
Advertisements
Question
The average number of phone calls per minute into the switchboard of a company between 10.00 am and 2.30 pm is 2.5. Find the probability that during one particular minute there will be no phone at all
Solution
The average number of phone cells per minute into the switchboard of a company is λ = 2.5
x follows poisson distribution with
P(x) = `("e"^(-lambda) lambda^x)/(x!)`
= `((2^(-2.5) (2.5)^x)/(x!))`
P(no phone at all) = P(X = 0)
= `("e"^(-2.5) (2.5)^0)/(0!)`
= `"e"^(-2.5)`
= 0.08208
APPEARS IN
RELATED QUESTIONS
Write down the condition for which the binomial distribution can be used.
In a family of 3 children, what is the probability that there will be exactly 2 girls?
Out of 750 families with 4 children each, how many families would be expected to have atleast one boy
Out of 750 families with 4 children each, how many families would be expected to have atmost 2 girls
An experiment succeeds twice as often as it fails, what is the probability that in next five trials there will be three successes
The mortality rate for a certain disease is 7 in 1000. What is the probability for just 2 deaths on account of this disease in a group of 400? [Given e–2.8 = 0.06]
The distribution of the number of road accidents per day in a city is poisson with mean 4. Find the number of days out of 100 days when there will be atleast 2 accidents
Choose the correct alternative:
A statistical analysis of long-distance telephone calls indicates that the length of these calls is normally distributed with a mean of 240 seconds and a standard deviation of 40 seconds. What proportion of calls lasts less than 180 seconds?
Choose the correct alternative:
The weights of newborn human babies are normally distributed with a mean of 3.2 kg and a standard deviation of 1.1 kg. What is the probability that a randomly selected newborn baby weight less than 2.0 kg?
Vehicles pass through a junction on a busy road at an average rate of 300 per hour. What is the expected number passing in two minutes?
