Given below are the marks secured by 35 students in a surprise test :
41,32 ,35, 21,11 ,47,42,00 ,05,18m,25,24,29,38,30, 04 ,14,24,34,44 ,48 ,33 ,36,38, 41,48 ,08 ,34 ,39,11,13,27,26,43,03
Taking class intervals 0-10,10-20,... construct frequency distribution table. Find the number of students obtaining below 20 marks