Find the mean of the following data:

x:	19	21	23	25	27	29	31
f :	13	15	16	18	16	15	13

If is the mean of the ten natural numbers, x₁, x₂, x₃,…., x₁₀, show that

(x₁-)+(x₂-)+ ….+(x₁₀-)= 0.

Calculate the mean for the following distribution:

Find the mean of the following data is 20.6. Find the value of p.

If the mean of the following data is 15. Find p.