laurab

I agree. You do not need to know much theory but hammer down the formulas. The essentials are st. dev, variance, and covariance. A lot of other answers and formulas are derived from these equations and knowing them is very important.
Spend one day, for a few hours and just learn the formulas and do a few practice problems with each to see how to implement them. You will be amazed at your progress.
Good luck!