What is the probability of getting at least $1$ tail when a coin is tossed $4$ times?

The probability mass function of a random variable $X$ is given by $P(X = x) = \frac{^5C_x}{2^5}$, for $x = 0, 1, 2, 3, 4, 5$ and $0$ otherwise. Which of the following is correct?

Five cards are drawn successively with replacement from a well-shuffled deck of $52$ cards. What is the probability that only $3$ cards are spades?

If a fair coin is tossed $10$ times,find the probability of exactly six heads.

The probability that a person who undergoes a certain operation will survive is $0.2$. If $5$ patients undergo similar operations,then the probability that exactly four will survive is

If $X$ and $Y$ are two independent binomial variates,satisfying $B(10, 1/2)$ and $B(8, 1/2)$ respectively,then the probability $P(X + Y = 2)$ is