Somi needs an average score of 80 in four exams to be successful in a competition. Her scores in the first three exams are 72, 82 and 92. What should she score in the fourth exam to be successful in the competition?

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).