Three persons work independently on a problem. If the respective probabilities that they will solve it are $\frac{1}{3}$,$\frac{1}{4}$,and $\frac{1}{5}$,then the probability that none of them can solve it is:

The probability that a non-leap year selected at random will have $53$ Sundays is

Two dice are thrown simultaneously. The probability of getting a multiple of $2$ on one die and a multiple of $3$ on the other die is

$A$ box $P$ contains one white ball,three red balls and two black balls. Another box $Q$ contains two white balls,three red balls and four black balls. If one ball is drawn at random from each one of the two boxes,then the probability that the balls drawn are of different colour is

$A$ coin is tossed. If it shows head,we draw a ball from a bag consisting of $3$ blue and $4$ white balls; if it shows tail,we throw a die. Describe the sample space of this experiment.

$A$ die has two faces each with number $1$,three faces each with number $2$,and one face with number $3$. If the die is rolled once,determine $P(1 \text{ or } 3)$.