The variance of the number of heads in 16 tosses of a coin is

If the mean of a binomial distribution is 12 and its standard deviation is 2, then the number of trials is :

The number of telephone calls made daily in a certain community between 8 P.M. and 9 P.M. has a mean of 352 and standard deviation of 31. What percentage of time will there be more than 400 telephone calls made in this community between 8 P.M. to 9 P.M.?

[Given that: $P(0\leq Z\leq1.55)=0.4394$, where $Z$ is the standard normal variate]

The variance of $X$ will be :

A box containing 10 wall clocks has three defective pieces in it. If random sample of two clocks is taken from the box, then the probability distribution of defective clocks is:

Let X denote the number of scores in a test. If X is normally distributed with mean 100 and standard deviation 15, then the probability that X does not exceed 130 is,

(Given $P(0 \le Z \le 2)=0.4772$, where $Z$ be the standard normal variate)

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