To receive Grade ‘A’ in a course, one must obtain an average of 90 marks or more in five examinations (each of 100 marks). If Sunita’s marks in first four examinations are 87, 92, 94 and 95, find minimum marks that Sunita must obtain in fifth examination to get grade ‘A’ in the course.

The marks obtained by a student of Class XI in first and second terminal examination are 62 and 48, respectively. Find the minimum marks he should get in the annual examination to have an average of at least 60 marks.

Ravi obtained 70 and 75 marks in first two unit test. Find the minimum marks he should get in the third test to have an average of at least 60 marks.

The following marks achieved by 30 candidates in mathematics of SSC examination held in the year 2010.45, 56, 75, 68, 35, 69, 98, 78, 89, 90, 70, 56, 59, 35, 46, 47, 13, 29, 32, 39,93, 84, 76, 79, 40, 54, 68, 69, 60, 59. Construct the frequency distribution table with the-class intervals, failed (0 – 34), third class (35 - 49), second class (50 - 60), first class (60 - 74) and distinction (75-100).