1) If brand A’s price varies over time and brand B’s price stays constant, the covariance between the two brands’ prices must be zero.
2) If the population is normally distributed we can always use the normal distribution to develop a confidence interval for the mean.
3) The expected value of a sample mean is the population mean only if the sample size is greater than or equal to 30.
4) The expected return of a portfolio of two tocks is higher when the covariance between the stock is positive than when the covariance is negative.
5) The more heterogeneous the population of interest is, the larger the sample we will have to estimate its mean with a given level of confidence and within a given margin of error.