If the mean of a set of observations x₁, x₂, x₃, ..., x₁₀ is 20, then the mean of x₁+5, x₂+10, x₃+15, ..., x₁₀+50 is:

The arithmetic mean of the series 1, 2, 4, 8, 16, ... 2ⁿ is

The mean of p, q, r, s and t is 280. If the mean of p, r and t is 240, what is the mean of q and s?

The mean of 100 observations was calculated as 49. It was later discovered that three observations taken as 40, 20, 50 were actually 60, 70, 80 respectively. The correct mean is

The arithmetic mean of the numbers 9, 12, 15, 18, 20, 22 is increased by 1, if 15 is replaced by

If M is the mean of the first 100 even natural numbers, then what is the mean of the first 100 odd natural numbers?