Question 1: Calculate the Mean and Standard Deviation for the following data: 

Answer:

Calculation of Mean, Variance and Standard Deviation

Question 2: Calculate the Standard Deviation  for the following data:

Answer:

Calculation of Mean, Variance and Standard Deviation

Question 3: Calculate the A.M and Standard Deviation  for the following distribution:

Answer:

Calculation of Mean, Variance and Standard Deviation

Question 4: A student obtained mean and standard deviation of 100 observations as 40 and 5.1  respectively. It was later found that one observation was wrongly copied as 50, the correct figure being 40. Find the correct mean and standard deviation.

Answer:

Variance

If 50 is replaced by 40

We know,

Question 5:  Calculate the mean, median and standard deviation  for the following distribution:

Answer: 

Calculation of Mean, Variance and Standard Deviation

Question 6: Calculate the mean and variance of frequency distribution given below:

Answer:

Calculation of Mean, Variance and Standard Deviation

Question 7: The weight of coffee in 70 jars is shown in the following table:

Determine the variance and standard deviation of the above distribution.

Answer:

Calculation of Mean, Variance and Standard Deviation

Question 8: The mean and standard deviation of 100 observations were found to be 40 and 10 respectively. If at the time of calculations two observations were wrongly taken as 30 and 70 in place of 3 and 27 respectively, find the correct standard deviation.

Answer:

Variance

If 30 and 70 are replaced by 3 and 27

We know,

Question 9: While calculating the mean and variance of 10 readings, a student wrongly used the reading of 52 for the correct reading 25. He obtained the mean and variance as 45 and 16 respectively. Find the correct mean and variance.

Answer:

Variance

If 52 is replaced by 25

We know,

Question 10: Calculate the mean, variance and standard deviation of the following frequency distribution:

Answer:

Calculation of Mean, Variance and Standard Deviation