Hi Milind,
The seeds question is Example 10, Chapter 15 of Class 9 - http://teachoo.com/1457/484/Example-10---Fifty-seeds-were-selected-at-random/category/Examples/
The frequency polygon question is Ex 14.3, 6 of Class 9 - https://www.teachoo.com/1415/479/Ex-14.3--6---The-table-gives-the-distribution-of-students/category/Ex-14.3/