The mean of 35 observations is 20. If the mean of the first 18 observations is 16 and that of last 18 observations is 24, find the 18th observation.

The mean of 35 observations in 20, out fo which mean of first 18 observation is 15 and mean of last 18 observation is 25, find the 18^(th) observations.

If the mean of 10 observations is 12, what is their sum?

Find the mode of the following observations:

The mean of the following observations is 20.2. Find the value of p.

The mean of the following observation is 20.2 . Find the value of p.

The mean of 5 observations is 4 and the variance is 5.2. If three of five observations are 1, 2 and 6, find the other two observations.