Three numbers are such that the average of first two numbers is 2, the average of the last two numbers is 3 and the average of the first and the last numbers is 4, then the average of three numbers is equal to. 

Some students (only boys and girls) from different schools appeared for an Olympiad exam. 20% of the boys and 15% of the girls failed the exam. The number of boys who passed the exam was 70 more than that of the girls who passed the exam'. A total of 90 students failed. Find the number of students that appeared for the exam.

The average of 5 numbers, arranged in a row, is 309. The average of the first two of these numbers is 431 and the average of the last two of these numbers is 231.5. What is the value of the number at the center of the row?

The average of 8 numbers is 27. If each of the numbers is multiplied by 8, find the average of new set of numbers.

The average of 5 numbers is 27. If one number is excluded, the average becomes 25. The excluded number is: 

The average monthly expenditure of a family for the first four months is ₹ 2570, for the next three months ₹ 2490 and for the last five months ₹3030. If the family saves ₹ 5320 during the whole year, the average monthly income of the family during the year is-

Average of 21 number is 36. If the average of first 12 numbers is 15, then find the average of remaining 9 number?

What is the average of all numbers between 100 and 200 which are divisible by 13?