Standard Deviation

I'm looking for a good definition of standard deviation and a full explanation of the concept, with a good example. Thanks!

X P(X=x) (5 @ .12) (6 @ .24) (8 @ .44) (10 @ .20) What is the standard deviation of X?

Use the data below to answer the determine variance and standard deviation. (note: carry your calculator out to 4 decimal places). Year Actual Return Average Return Deviation for the Mean Squared Deviation 1 .12 .103 .017

Find the standard deviation of the data in the given frequency table. A company had 80 employees whose salaries are summarized in the frequency table below. Find the standard deviation. Salary Employees 5001-10000 17 10001-15000 16 15001-20000 20 20001-25000 15 25001-30000 12

Mean = 24...... std dev =25..... meaning of data?

Find the standard deviation. Round to one more place than the data. 20, 18, 12, 8, 7, 5, 12, 11, 9

Determine the mean and the standard deviation of the following frequency distribution. CLASS FREQUENCY 0 UP TO 5 2 5 UP TO 10 7 10 UP TO 15 12 15 UP TO 20 6 20 UP TO 25

State of the economy Probability End of Period Return Stock A Stock B Good 0.3 20% 21% Average 0.5 16%

Year actual return actual return deviation squared deviation 1 -14.69 .05 2 -26.47 .05 3 37.23 .05 4 23.93 .05 5 -7.16 .05 6 6.57 .05 7 18.67

You own a portfolio that has 35% invested in asset A, and 65% invested in asset B. Asset A's standard deviation is 12% and asset B's standard deviation is 18%. The correlation coefficient between the two assets is -0.7. The expected return on the portfolio is 13%. What is the portfolio standard deviation? 1. 8.5% 2. 9.3%