I am having problems understanding two questions from the CFA book, could anyone help me to understand?
Q: Over the past 240 months, an investor’s portfolio had a mean monthly return of 0.79%, with a standard deviation of monthly returns of 1.16%. According to Chebyshev’s inequality, the minimum number of the 240 monthly returns that fall into the range of −0.95% to 2.53% is closest to: A 80. B 107. C 133.
Q: For a distribution of 2,000 observations with finite variance, sample mean of 10.0%, and standard deviation of 4.0%, what is the minimum number of observations that will lie within 8.0% around the mean according to Chebyshev’s Inequality? A 720 B 1,500 C 1,680
You don’t have to calculate the standard deviation; it’s given, as you say.
I’m not asking you to calculate the standard deviation. I’m asking _ how many _ (4%) standard deviations is 8%? Is it one standard deviation? Three? 6.5? 0.8? How many?