$A$ lot consists of $12$ good pencils,$6$ with minor defects,and $2$ with major defects. $A$ pencil is chosen at random. The probability that this pencil is not defective is

The probabilities of solving a specific problem independently by $A$ and $B$ are $\frac{1}{2}$ and $\frac{1}{3}$ respectively. If both try to solve the problem independently,find the probability that the problem is solved.

Three boxes contain respectively $3$ white and $1$ black,$2$ white and $2$ black,$1$ white and $3$ black balls. From each of the boxes,one ball is drawn at random. The probability that $2$ white and $1$ black balls will be drawn is:

$A$ die is thrown. Describe the following events: $A$: a number less than $7$,$B$: a number greater than $7$,$C$: a multiple of $3$. Find $B \cup C$.

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

If a leap year is selected at random,what is the chance that it will contain $53$ Tuesdays?