I think i got it. 

Can someone please double check?

SELECT d.date_, SUM(w.workout_hours) AS Total_Workout_High, SUM(w.workout_hours) AS Total_Workout_Low
    FROM workout_table w
JOIN
athlete_table a ON...

Can anyone help with this question please?:

Create a table to show the aggregate workout hours for each “Hard” and “Basic” level of workout endurance by day:

Here's the code to create the table:

CREATE TABLE track_table (date_ VARCHAR(4), athleteID VARCHAR(1));

INSERT...

If you could help me with question 3 in particular please?

A distribution of # days active within a week: Create a table to show how many athletes...

Correct.  I think it's just poorly worded.  Creating tables doesn't make sense.  But are instead SELECT commands.

Sorry that was my mistake.

If you could or if anyone else could please assist, that would be greatly appreciated =