If $8$ coins are tossed simultaneously,what is the probability of getting at least $6$ heads?

The probability of a shooter hitting a target is $\frac{3}{4}$. What is the minimum number of times he/she must fire so that the probability of hitting the target at least once is greater than $0.99$?

On an average, nine out of $10$ ships that have departed at $A$ reach $B$ safely. The probability that out of five ships that have departed at $A$, at least four will reach $B$ safely is

In a bombing attack,there is a $50 \%$ chance that a bomb will hit the target. At least two independent hits are required to destroy the target completely. Then the minimum number of bombs that must be dropped to ensure that there is at least a $99 \%$ chance of completely destroying the target is:

For an entry to a certain course,a candidate is given $20$ problems to solve. If the probability that the candidate can solve any problem is $\frac{3}{7}$,then the probability that he is unable to solve at most $2$ problems is

The probability that a student is a singer is $\frac{1}{5}$. Then,the probability that $4$ students are singers out of $5$ students is . . . . . . .