The mean 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 were omitted.

The mean 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.

The mean and standard deviation of 20 observations are found to be 10 and 2. respectively. On rechecking, it was found that an observation 8 was incorrect. Calculate the correct mean and standard deviation in each of the following cases: (i) If wrong item is omitted. (ii) If it is replaced by 12.

The mean and standard deviation of 100 observations were calculated as 40 and 5.1 respectively by a student who took by mistake 50 instead of 40 for one observation. What are the correct mean and standard deviation ?

The mean and standard deviation of six observations are 8 and 4, respectively. If each observation is multiplied by 3, find the new mean and new standard deviation of the resulting observations.

Mean of 50 observations was found to be 80.4. but later on, it was discovered that 96 was misread as 69 at one place. Find the corect mean.

From 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. Calculate the correct mean and standard deviation.

The mean of 100 items was found to be 64. later on, it was discovered that two itens were misread as 26 and 9 instead of 36 and 90 respectively. Find the correct mean.

A scientist is weighting each of 30 fishes. Their mean weight worked out as 30 gm and standard derivation of 2gm. Later, it ways found that the measuring scale was misaligned and always under reported every fish by 2gm. The correct mean and standard deviation (in gm) of fishes are respectively :