This mock follows the format of task-based Excel certification exams such as Microsoft's MO-200 (Excel Associate): one workbook, a list of short tasks, a clock. The questions are our own; it's practice, not an official exam.
Each task has 2 minutes 30 seconds on the clock in the sheet. Work quickly, but read the task twice: exams mark the exact range and the exact result. Use the ribbon or the keyboard, whichever is faster for you.