Of the $50$ students in a class, $22$ are girls. The probability that a student who gets first rank is a boy is .............

When a balanced die is thrown,find the probability of getting an odd number.

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

$A$ 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 under $60$ but over $39$ years.

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

As the number of tosses of a coin increases,the ratio of the number of heads to the total number of tosses will be $\frac{1}{2}$. Is it correct? If not,write the correct one.