Standard error of mean =σ√n=12√100=1.2 (σ= S.D. of sample, n = size of the sample
A sample of 35 observations has the mean 80 and standard deviation as 4. A second sample of 65 observations from the same population has mean 60 and standard deviation 3. Then the standard deviation of the combined sample is
The mean and standard and standard deviation of a group of 100 observations were found to be 20 and 3 respectively. Later on it was found that three observations were incorrect, which were recorded as 21, 21 and 18. Find the mean and standard deviation if the incorrect observations are omitted.
Mean and standard deviation of 100 observations were found to be 40 and 10 respectively. If at the time of calculation two observations were wrongly taken as 30 and 70 in place of 3 and 27 respectively, Find the correct standard deviation.
For a frequency distribution consisting of 18 observations, the mean and the standard deviation were found to be 7 and 4 respectively. But on comparison with the original data, it was found that a figure 12 was miscopied as 21 in calculations. Find the correct mean and standard deviation.___