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.

Raju obtained 70 and 60 marks in first two examinations. Find the minimum mark he should get in the third examination to have an average of atleast 50 marks.

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

Arathi took 3 examinations in an year. The marks obtained by her in the second and third examinations are more than 5 and 10 respectively than in the first examination. If her average mark is at least 80 find the minimum mark that she should get in the first examination?

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

Marks obtained in mathematics examination are given below:(ii)Find variance of the marks.

Marks obtained in mathematics examination are given below:(iii)Find standard deviation of marks

In the first four examinations each of 100 marks, Hamid got 94,73,72,84 marks. If a final average greater than or equal to 80 and less than 90 is needed to obtain a final grade B in a course, what range of marks on the fifth(last) examination will result in Hamid receiving ''B'' in the course?

In a class, in an examination in Mathematics, 10 students scored 100 marks each 2 students scored zero and the average of the remaining students is 72 marks. If the class average is 76, then the number of students in the class is