In a single throw of a die, if X denotes the number on its upper face, then the mean of X is,

There are 50 telephone lines in an exchange. If the probability that any one of them will be busy is 0.1, then the probability that all the lines are busy is

A telephone exchange receives on an average 5 calls per minute. The probability of receiving 3 or less calls per minute is :

If X has a Poisson distribution such that $2P(X=1)=P(X=2)$, then which of the following are correct?

A. The mean of X is 4

B. The mean of X is 2

C. $P(X=2)=\frac{8}{e^4}$

D. $P(X=3)=\frac{32}{e^4}$

Choose the correct answer from the options given below:

In a binomial distribution the probability of getting success is $\frac{1}{4}$ And standard deviation is 3 then its mean is ?

If a coin is tossed 8 times and getting a head is considered as success, then which of the following statements are correct ?

(A) The probability of getting 4 heads is $\dfrac{35}{128}$

(B) The mean of the number of successes is 4.

(C) The variance of the number of successes is 2.

(D) The probability of getting 6 heads is $\dfrac{9}{64}$.

Choose the correct answer from the options given below:

The mean and variance of a Binomial distribution are 4 and 4/3 respectively. The number of trials is