$5.[$Total $15$ marks$]$

Following the stock time series application context of Question $3$ and by referring to Table V of Question $3,$ you are asked the following questions related to data warehousing.

$($a$)$ What data cleaning tasks are typically involved?

$(4$ marks$)$

$($b$)$ Give an example of a $3$D data cube for this application context. Describe the $3$ dimension tables involved. Note that you are not limited to the data in Table V and can refer to the application context generally.

$(4$ marks$)$

$($c$)$ Based on your answer in part $($b$),$ describe how OLAP operations Roll Up and Drill Down work.

$(4$ marks$)$

$($d$)$ Following parts $($b$)\backslash$& $($c$),$ give an example of possible enquiry of the stock time series data in a data warehouse setting.