In a binomial distribution,the mean is $15$ and the variance is $10$. Then the parameter $n$ is:

$A$ die is thrown five times. If getting an odd number is a success,then the probability of getting at least $4$ successes is

From a lot of $30$ bulbs which include $6$ defectives,a sample of $4$ bulbs is drawn at random with replacement. Find the probability distribution of the number of defective bulbs.

$A$ coin is tossed successively three times. The probability of getting exactly one head or $2$ heads is:

$A$ coin is biased so that a head is twice as likely to occur as a tail. If the coin is tossed $3$ times,then the probability of getting two tails and one head is-

$A$ dice is thrown two times. If getting an odd number is considered a success,then the probability of two successes is