The following frequency distribution table shows the blood groups of $30$ students of a class. Use this table to determine the probability that a student of this class,selected at random,has blood group $AB$.

Blood group	Number of students
$A$	$9$
$B$	$6$
$AB$	$3$
$O$	$12$
Total	$30$

The record of a weather station shows that out of the past $250$ consecutive days,its weather forecasts were correct $175$ times.
$(i)$ What is the probability that on a given day it was correct?
$(ii)$ What is the probability that it was not correct on a given day?

Two coins are tossed simultaneously $500$ times,and we get:
Two heads : $105$ times
One head : $275$ times
No head : $120$ times
Find the probability of occurrence of each of these events.

An organisation selected $2400$ families at random and surveyed them to determine a relationship between income level and the number of vehicles in a family. The information gathered is listed in the table below:

Monthly income (in Rs.) / Vehicles per family	$0$	$1$	$2$	Above $2$
Less than $7000$	$10$	$160$	$25$	$0$
$7000 - 10000$	$0$	$305$	$27$	$2$
$10000 - 13000$	$1$	$535$	$29$	$1$
$13000 - 16000$	$2$	$469$	$59$	$25$
$16000$ or more	$1$	$579$	$82$	$88$

Suppose a family is chosen. Find the probability that the family chosen is:
$(i)$ Earning Rs. $10000 - 13000$ per month and owning exactly $2$ vehicles.
$(ii)$ Earning Rs. $16000$ or more per month and owning exactly $1$ vehicle.
$(iii)$ Earning less than Rs. $7000$ per month and does not own any vehicle.
$(iv)$ Earning Rs. $13000 - 16000$ per month and owning more than $2$ vehicles.
$(v)$ Owning not more than $1$ vehicle.

Find the probability that a student of the class was born in August.

$A$ teacher wanted to analyze the performance of two sections of students in a mathematics test of $100$ marks. Looking at their performances,she found that a few students got under $20$ marks and a few got $70$ marks or above. So she decided to group them into intervals of varying sizes as follows: $0-20, 20-30, ..., 60-70, 70-100$. Then she formed the following table:

Marks	Number of students
$0-20$	$7$
$20-30$	$10$
$30-40$	$10$
$40-50$	$20$
$50-60$	$20$
$60-70$	$15$
$70$ and above	$8$
Total	$90$

$(i)$ Find the probability that a student obtained less than $20\%$ in the mathematics test.
$(ii)$ Find the probability that a student obtained marks $60$ or above.