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 $1685) (in $1,6885) 26 29 21 17 27 19 29 17 32 25 22 16 Ii 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 O No correlation 0 Positive correlation cl. Calculate the correlation coefcient between advertising and sales. (Round your answer to 2 decimal places.) Correlation coefcient