Are some people bad at math?
No. I believe everyone has the same capability to get any basic math question right, since there is only one answer. The difference between "math" people and those who claim they aren't naturally good at math is the learning techniques they are trying to use and the ones they haven't tried yet.
Is there a way to memorize statistics?
I have been very successful in my statistics classes once I realized I cannot treat them like math classes. Answers in statistics usually aren't graded as right or wrong like they are in math classes, which can be a disadvantage to those who rely on the consistency of formulas and methods to double-check your work. To do well in statistics classes, it is vital that you understand the reasoning behind the calculations and the meaning of the answers you're looking for.
What is the importance of understanding basic finance, accounting and marketing in any business major?
All business majors should have a basic understanding of these three concepts, even if they don't seem relevant to the subject itself. Basic finance classes require you to understand financial markets, compare and evaluate companies, and form an appropriate financial structure based on a relevant forecast of the companies and the markets future condition. Basic marketing classes will help you understand how to price products and services based on of their research and development expenses, the cost to make the products, the cost to promote and sell the products, and the predicted condition of the market demand. Finance and Marketing classes will both require some simple statistics. Basic accounting is important to understand because there are very particular rules on the way companies record financial information that can effect finance and marketing decisions. Although accounting has a reputation of being the hardest of the three in college classes, the practice itself is repetitive and surprisingly simple once you catch on.