If the arithmetic mean of seventy-five numbers us calculated, it is 35. If each number is increased by 5, then mean of n…

The average age of four boys A, B, C and D is 5 years and the average age A, B, D, E is 6 years. C is 8 years old. The a…

If 25a + 25b = 115, what is the average of a and b?

The average age of 40 students of class is 18 years. When 20 new students are admitted to the same class, the average ag…

If the mean of 4 observations is 20, when a constant 'c' is added to each observation, the mean becomes 22. The value of…

The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, then …

What is the average of the first six (positive) odd number each of which is divisible by 7?

The average age of a family with 5 members is 28. If one of the 5 members of age 20 is excluded the average age of the f…