What activities occur during the discovery phase of the data analytics lifecycle?

Which data asset is an example of quasi-structured data?

Data visualization is used in the final presentation of an analytics project.
For what else is this technique commonly used?

When is the GROUP BY ROLLUP clause used in an OLAP query?

A data scientist is given an R data frame (i.e., empdata) with the following columns: Age Salary Occupation Education Gender The scientist wants to examine only the Salary and Occupation columns for ages greater than '40'.
Which command extracts the appropriate rows and columns from the data frame?