The average weight of 18 students is 54 kg. After including a new student in that group, the average weight rises by 1 kg. What is the weight of the new student?

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).