Two sets each of 20 observations have the same standard derivation 5. The first sethas a mean 17 and second a mean 22. Then the standard deviation of the set obtained by combining the given two sets.

Two sets each of 20 observations , have the same standard deviation 5. The first set has a mean 17 and the second a mean 22. Determine the standard deviation of the set obtained by combining the given two sets.

Two sets each of 20 observations, have the same standard deviation 5 . The first set has a mean 17 and the second set mean 22 then the standard deviation of the combining the given two sets is

The means of two samples of sizes 10 and 20 respectively are 24 and 45 and the standard deviations are 6 and 11. Obtain the standard deviation of the sample of size 30 obtained by combining the two samples. (sqrt19067=138)

A sample of 35 observations has mean 80 men and standard deviation 4. A second sample of 65 observations has mean 70 and standard deviation =3. Find the combined mean and standard deviation.