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?

If $X \sim B(n, p)$, then the value of $\frac{P(X = k)}{P(X = k - 1)}$ is

The items produced by a firm are supposed to contain $5\%$ defective items. The probability that a sample of $8$ items will contain less than $2$ defective items is:

When six coins are tossed simultaneously,the probability of getting at least $4$ heads is

An objective type test paper has $5$ questions. Out of these $5$ questions, $3$ questions have four options each $(a, b, c, d)$ with one option being the correct answer. The other $2$ questions have two options each, namely true and false. $A$ candidate randomly ticks the options. Then, the probability that he/she will tick the correct option in at least four questions, is

If a variable takes values $0, 1, 2, \dots, n$ with frequencies ${q^n}, \frac{n}{1}{q^{n - 1}}p, \frac{n(n - 1)}{1 \times 2}{q^{n - 2}}{p^2}, \dots, {p^n}$,where $p + q = 1$,then the mean is