In an oratory competition,$30$ students participated,out of which $12$ are boys. Find the probability that the first prize is won by a girl.

$A$ recent survey found that the ages of workers in a factory is distributed as follows:

Age (in years)	$20-29$	$30-39$	$40-49$	$50-59$	$60$ and above
Number of workers	$38$	$27$	$86$	$46$	$3$

If a person is selected at random,find the probability that the person is $40$ years or more.

The probability of a certain event is ........

Can the experimental probability of an event be a negative number? If not,why?

From the list of telephone numbers of $100$ employees of a factory, the following frequency distribution of their unit place digit (for example, in the number $25828573$, the unit place digit is $3$) is given in the table below:

Unit digit	$0$	$1$	$2$	$3$	$4$	$5$	$6$	$7$	$8$	$9$
Frequency	$8$	$9$	$12$	$15$	$10$	$7$	$12$	$10$	$9$	$8$

Find the probability that a randomly selected employee has a telephone number with unit digit $3$.

Here is an extract from a mortality table.

Age (in years)	Number of persons surviving out of a sample of one million
$60$	$16090$
$61$	$11490$
$62$	$8012$
$63$	$5448$
$64$	$3607$
$65$	$2320$

What is the probability that a person aged $61$ will live for $4$ years?