Mode of the data $15, 14, 19, 20, 14, 15, 16, 14, 15, 18, 14, 19, 15, 17, 15$ is

Find the mean of the observations $15, 22, 18, 27, 31, 21, 14, 36, 25$ and $34$.

The number of books in different shelves of a library are as follows:
$37, 22, 24, 27, 28, 27, 20, 36, 21, 20,$
$29, 30, 29, 36, 30, 25, 27, 32, 24, 28,$
$34, 20, 25, 28, 30, 20, 35, 25, 27, 31$
Represent the data given above by a grouped frequency distribution table,taking the class intervals as $18-22, 22-26, 26-30, 30-34, 34-38$.

Give five examples of secondary data that you can collect from your day-to-day life.

If the information gathered by an investigator is from an already existing source of data,then such information is called .........

For the following data,draw a frequency polygon:

Class	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$	$60-70$	$70-80$
Frequency	$1$	$4$	$5$	$10$	$5$	$4$	$1$