A manager of a local retail store analyzes the relationship between advertising and sales by reviewing the store's data for the previous six months. Advertising Sales (in $1965) (in 51,8985) 23 23 27 26 24 24 3B 26 21 23 21 21 Click here for the Excel Data File a. Calculate the mean of advertising and the mean of sales. (Round your answers to 2 decimal places.) Advertising Sales b. Calculate the standard deviation of advertising and the standard deviation of sales. (Round your answers to 2 decimal places.) Advertising Sales c-1. Calculate the covariance between advertising and sales. [Round your answer to 2 decimal places.) c-2. Interpret the covariance between advertising and sales. 0 Negative correlation 0 Positive correlation O No correlation d. Calculate the correlation coefficient between advertising and sales. {Round your answer to 2 decimal places} Correlation coefcient [