Assume we have a data cube consisting of three dimensions: Product, Time, and Location. The values $($i$.$e$.,$ facts$)$ show the revenue in thousands of dollars. Which OLAP operations should be performed in order to answer the following questions: a$.)$ Total revenue earned by selling DVDs in British Columbia in $2010.$ b$.)$ Total revenue earned by each product in each province. Time $2/3/20103/3/2010$ Toronto Ottawa Product PC Printer DVD $100907080|23|35212040182835$ Location Victoria Vancouver $110896285$ Assume we have the following hierarchy: TIME LOCATION year country month $|$ date province $|$ city