The blood groups of $30$ students of Class $VIII$ are recorded as follows:
$A, B, O, O, AB, O, A, O, B, A, O, B, A, O, O,$
$A, AB, O, A, A, O, O, AB, B, A, O, B, A, B, O.$
Represent this data in the form of a frequency distribution table. Which is the most common,and which is the rarest,blood group among these students?

The heights (in $cm$) of $9$ students of a class are as follows:
$155, 160, 145, 149, 150, 147, 152, 144, 148$
Find the median of this data. (in $\text{ cm}$)

The heights of $50$ students,measured to the nearest centimetres,have been found to be as follows:
$\begin{array}{llllllllll}161 & 150 & 154 & 165 & 168 & 161 & 154 & 162 & 150 & 151 \\ 162 & 164 & 171 & 165 & 158 & 154 & 156 & 172 & 160 & 170 \\ 153 & 159 & 161 & 170 & 162 & 165 & 166 & 168 & 165 & 164 \\ 154 & 152 & 153 & 156 & 158 & 162 & 160 & 161 & 173 & 166 \\ 161 & 159 & 162 & 167 & 168 & 159 & 158 & 153 & 154 & 159\end{array}$
$(i)$ Represent the data given above by a grouped frequency distribution table,taking the class intervals as $150-155, 155-160,$ etc.
$(ii)$ What can you conclude about their heights from the table?

The relative humidity (in $\%$) of a certain city for a month of $30$ days was as follows:

$98.1$	$98.6$	$99.2$	$90.3$	$86.5$	$95.3$	$92.9$	$96.3$	$94.2$	$95.1$
$89.2$	$92.3$	$97.1$	$93.5$	$92.7$	$95.1$	$97.2$	$93.3$	$95.2$	$97.3$
$96.2$	$92.1$	$84.9$	$90.2$	$95.7$	$98.3$	$97.3$	$96.1$	$92.1$	$89$

$(i)$ Construct a grouped frequency distribution table with classes $84-86, 86-88$,etc.
$(ii)$ Which month or season do you think this data is about?
$(iii)$ What is the range of this data?

The following table gives the life times of $400$ neon lamps:

The time (in hours)	Number of lamps
$300-400$	$14$
$400-500$	$56$
$500-600$	$60$
$600-700$	$86$
$700-800$	$74$
$800-900$	$62$
$900-1000$	$48$

$(i)$ Represent the given information with the help of a histogram.
$(ii)$ How many lamps have a life time of more than $700$ hours?

The distances (in $km$) of $40$ engineers from their residence to their place of work were found as follows:

$5$	$3$	$10$	$20$	$25$	$11$	$13$	$7$	$12$	$31$
$19$	$10$	$12$	$17$	$18$	$11$	$32$	$17$	$16$	$2$
$7$	$9$	$7$	$8$	$3$	$5$	$12$	$15$	$18$	$3$
$12$	$14$	$2$	$9$	$6$	$15$	$15$	$7$	$6$	$12$

Construct a grouped frequency distribution table with class size $5$ for the data given above,taking the first interval as $0-5$ ($5$ not included). What main features do you observe from this tabular representation?