How many times must a fair coin be tossed so that the probability of getting at least one head is at least $0.8$?

An irregular six-faced die is thrown. The probability that in $5$ throws it will give $3$ even numbers is twice the probability that it will give $2$ even numbers. The number of times,in $6804$ sets of $5$ throws,you expect to get no even number is:

In a box containing $100$ bulbs,$10$ are defective. The probability that out of $20$ bulbs selected at random,none is defective is

Two cards are drawn successively with replacement from a well-shuffled pack of $52$ cards. Then the probability distribution of the number of jacks is:

In a university campus, the probability that a person chosen at random is an engineering student is $\frac{1}{5}$. The probability of having at most two engineering students in a sample of $8$ people is:

Suppose a machine produces metal parts that contain some defective parts with probability $0.05$. How many parts should be produced in order that the probability of at least one part being defective is at least $1/2$? (Given that, $\log_{10} 95 = 1.977$ and $\log_{10} 2 = 0.3$)