Let $m$ be the mid-point and $l$ be the upper class limit of a class in a continuous frequency distribution. The lower class limit of the class is:

Convert the given frequency distribution into a continuous grouped frequency distribution:

Class interval	Frequency
$150-153$	$7$
$154-157$	$7$
$158-161$	$15$
$162-165$	$10$
$166-169$	$5$
$170-173$	$6$

In which intervals would $153.5$ and $157.5$ be included?

The following table shows a frequency distribution for the speed of cars passing through a particular spot on a highway:

Class interval $(km/h)$	Frequency
$30-40$	$3$
$40-50$	$6$
$50-60$	$25$
$60-70$	$65$
$70-80$	$50$
$80-90$	$28$
$90-100$	$14$

Draw a histogram and a frequency polygon representing the data above.

Obtain the mean of the following distribution:

Frequency $(f_i)$	Variable $(x_i)$
$4$	$4$
$8$	$6$
$14$	$8$
$11$	$10$
$3$	$12$

The mean of the data $\frac{4}{7}, \frac{4}{9}, \frac{3}{7}, \frac{5}{9}$ is ........

Find the median of the observation: $62, 67, 82, 71, 75, 77, 63, 91$.