Find the mean and median of the data :

35, 48, 92, 76, 64, 52, 51, 63 and 71.

If 51 is replaced by 66, what will be the new median ?

The mean of x, x + 2, x + 4, x + 6 and x + 8 is 11, find the mean of the first three observations.

The mean weight of 60 students in a class is 40 kg. The mean weight of boys is 50 kg while that of girls is 30 kg. Find the number of boys and girls in the class.

The average of n numbers x₁, x₂, x₃ ……………, x_n is A. If x₁ is replaced by (x + a)x₁, x₂ is replaced by (x + a)x₂ and so on. Find the new average.