In a frequency distribution, the mid-value of the class is $10$ and width of the class is $6$. Find the lower limit of the class.

The class marks of a frequency distribution are $15, 20, 25,...$. Find the class corresponding to the class mark$20$.

Find the values of $a, b, c, d, e, f, g$from the following frequency distribution of the heights of $50$ students in a class:

$\begin{array}{|ccc|}\hline \text{ Height (in cm) }& \text{ Frequency }& \begin{array}{c}\text{ Cumulative }\\ \text{ frequency }\end{array}\\ 160-165& 15& a\\ 165-170& b& 35\\ 170-175& 12& c\\ 175-180& d& 50\\ 180-185& e& 55\\ 185-190& 5& f\\ & g& \\ \hline\end{array}$

The range of the data

$12, 25, 15, 18, 17, 20, 22, 6, 16, 11, 8, 19, 10, 30, 20, 32$ is