Find the probability of getting $51$ marks out of $50$ marks.

At a fair, $70$ boys, $80$ girls, $20$ men, and $30$ women have come. Find the probability that a person selected at random to be a prize winner is a woman.

In a medical examination of students of a class,the following blood groups are recorded:

Blood group	$A, AB, B, O$
Number of students	$10, 13, 12, 5$

$A$ student is selected at random from the class. The probability that he/she has blood group $B$,is:

Bulbs are packed in cartons,each containing $40$ bulbs. Seven hundred cartons were examined for defective bulbs,and the results are given in the following table:

Number of defective bulbs	$0$	$1$	$2$	$3$	$4$	$5$	$6$	more than $6$
Frequency	$400$	$180$	$48$	$41$	$18$	$8$	$3$	$2$

One carton was selected at random. What is the probability that it has less than $4$ defective bulbs?

In cricket,Rohit hits a century in $4$ innings out of $10$ innings. Find the probability that he did not hit a century.

The distribution of the weights of $50$ students in a class is as follows:

Weight (in $kg$)	Number of students
$50-52$	$10$
$52-54$	$12$
$54-56$	$13$
$56-58$	$9$
$58-60$	$6$

Find the probability that a student selected at random weighs $56 \ kg$ or more.