The average of 5, 10, 15, and x is 20. What is the value of x?

Mean of 5 numbers is 18. Four numbers are 16, 18, 14, and 22. The 5th number is:

The average of 3 numbers is 26. If the first number is 16 and the second is 31, the third number is:

The arithmetic mean of 2, 4, 6, 8 is:

If the average of 5 students is given and one student leaves, how is the new average calculated?

If 8 persons have an average of 12.5 and one person of 18 kg is replaced with 10 kg, the new average will be:

The numbers 7, 6, 10, 8, and 9 have frequencies 2, 2, 5, 1, and 2. Find their mean.