$A$ problem in mathematics is given to $4$ students whose chances of solving it individually are $\frac{1}{2}, \frac{1}{3}, \frac{1}{4},$ and $\frac{1}{5}.$ The probability that the problem will be solved by at least one student is

$A$ card is selected from a pack of $52$ cards. Calculate the probability that the card is an ace.

Two unbiased dice are thrown. Then the probability that neither a doublet nor a total of $10$ will appear is

If the roots of each of the equations $2x^2+x-1=0$, $3x^2-10x+3=0$, and $6x^2+11x-2=0$ correspond to probabilities of three events of a random experiment, then those events are

Let $S$ be the sample space of the random experiment of throwing simultaneously two unbiased dice and $E_k = \{(a, b) \in S : ab = k\}$. If $p_k = P(E_k)$, then which of the following is correct?

Two students,Anil and Ashima,appeared in an examination. The probability that Anil will qualify the examination is $0.05$ and that Ashima will qualify the examination is $0.10$. The probability that both will qualify the examination is $0.02$. Find the probability that only one of them will qualify the examination.