The average age of 31 students of a class is 30 years. If the age of the teacher is also included, the average age of the whole group becomes 31 years. The age (in years) of the teacher is:

The average of 50 numbers is 38 . If two numbers 45 and 55 are excluded, then what will be the average of the remaining numbers?

A student's marks were incorrectly entered as 24 instead of 52. Due to this error, the average marks of the class decreased by 1.4. What is the number of students in the class?

The average age of 14 persons is 13 years. If the age of 15th persons is added, then the average remains same. What is the age (in years) of the 15th person?

Average of 6 numbers is P. One number is removed. New average is P + 5. Which number was removed?

Average age of a group of 16 boys is 24 years. Two boys with ages 19 years and 18 years left the group. One boy with age 43 years joined the group. What is the new average age (in years) of the group?

Average of 7 numbers is 28. One of these numbers is 22. 22 is replaced with a new number. New average becomes 30. What is that new number?

In a class, the average age of 28 boys is 13 years. Two boys whose ages are 'x' years and 21 years leave the class. If the new average age of the class is 13 years, then what is the value of 'x'?

A batsman has a certain average after 16 innings. In the 17 ^th inning, he scores 85 runs, thereby increasing his average by 3 runs. What is his new average ?

A set of fifteen numbers has an arithmetic mean of 42 . The mean of the first eight numbers is 39 , while the mean of the last eight numbers is 44 . The value of the eighth number is