It is observed that $30 \%$ of the students appearing for a certain entrance test are science students. If $5$ students are randomly selected from this group,the probability of having $2$ science students among these students is

Five cards are drawn successively with replacement from a well-shuffled deck of $52$ cards. What is the probability that all the five cards are spades?

$A$ die is thrown $100$ times. If the success is defined as getting an even number,then the variance of the number of successes is:

Ten eggs are drawn successively with replacement from a lot containing $10 \%$ defective eggs. Find the probability that there is at least one defective egg.

The probability that a bulb produced by a factory will fuse after $150$ days of use is $0.05$. Find the probability that out of $5$ such bulbs,at least one will fuse after $150$ days.

$A$ target is to be destroyed in a bombing exercise and there is a $75 \%$ chance that a bomb will hit the target. Assuming that two direct hits are required to destroy the target completely,the minimum number of bombs to be dropped in order that the probability of destroying the target is not less than $99 \%$,is