$A$ box contains $10$ good articles and $6$ defective articles. One article is chosen at random. What is the probability that it is either good or defective?

In the following experiment,specify the appropriate sample space: $A$ person is noting down the number of accidents along a busy highway during a year.

Let $S$ be the set of all quadratic equations of the form $x^2+bx+c=0$,where $b, c \in \{1, 2, 3, 4, 5, 6\}$. If an equation is selected at random from $S$,then the probability that the equation has real roots is

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 probabilities of an anti-aircraft gun shooting down an enemy plane in the first,second,and third shots are $0.6, 0.7$,and $0.1$ respectively. What is the probability that the gun shoots down the plane?

One card is drawn from each of two ordinary packs of $52$ cards. The probability that at least one of them is an ace of hearts is: