The average weight of 17 students of a class is 56 kg. Three new students whose weights are 57 kg, 62 kg, and 68 kg, respectively, join the class. Find the new average weight of the students of the class.

The average of 100 numbers is 40. If one of the numbers, 30, is replaced by 70 while keeping the other numbers same, what is the new average?

The arithmetic mean of 22.5, 56, 42.5, 2x + 1, x - 2, 3x, and 36 is 30. Find the value of x (where x > 0).