VERY IMPORTANT QUESTION FOR THE EXAM, PAY ATTENTION
1) To find the number of days between order date and shipping date, we will make use of a calculated field:

In the data pane, click on the dropdown arrow, and choose create calculated field.
Let's name this calculated field "ShippingDelay" (you can name it anything you want :) )
2) Use the DATEDIFF() function, and pass it the arguments as follows:

'day' depicts that we want to calculate the number of DAYS between the two dates. The first argument is
'start_date' which is the ORDER_DATE (day the order was placed), the second argument is 'end_date', which is the SHIP_DATE (date the order was shipped). So by subtracting as follows: SHIP_DATE - ORDER_DATE, we can find the delay in shipping.
Click OK.
3) You should now have a new measure as follows:

4) Phew! The hard part is done! Now let's filter by Market to include only LATAM:

5) Drag Country to the view, and the new calculated field 'ShippingDelay' to SIZE on the Marks Shelf as follows:
*You can also click on Show Text Labels to be sure that you're choosing the Largest value*

Clearly, Mexico has the highest Shipping Delay!

Presently, there is no official way to connect your data in Firebase directly with Tableau Desktop.
A workaround however can be to export your Firebase data into Google BigQuery, and then connect it to Tableau Desktop.
But then again, it is a workaround and not an official out-of-the-box solution.
The following are the available Data sources available as of now:
1) Server

2) File

You can combine two sets to compare the members. When you combine sets you create a new set containing either the combination of all members, just the members that exist in both, or members that exist in one set but not the other.
Combining sets allows you to answer complex questions and compare cohorts of your data. For example, to determine the percentage of customers who purchased both last year and this year, you can combine two sets containing the customers from each year and return only the customers that exist in both sets.
To combine two sets, they must be based on the same dimensions. That is, you can combine a set containing the top customers with another set containing the customers that purchased last year. However, you cannot combine the top customers set with a top products set.

To add totals to a view using the Analytics pane:

Also, you can add totals from the Analytics tab in the Menu above:

The following options are available in the Device preview section when creating a Dashboard: