Statistics, Probability, and Discrete Mathematics
This domain spans data analysis, probability, and discrete topics such as counting and logic. Know measures of center (mean, median, mode) and spread (range, interquartile range, standard deviation qualitatively), how outliers affect the mean versus the median, and how to read and interpret data displays (histograms, box plots, scatterplots). For probability, understand sample spaces, independent vs. dependent events, conditional probability, and the complement rule. Discrete topics include the fundamental counting principle, permutations vs. combinations, and basic set and logic ideas.
Traps: using the mean when the median better describes skewed data; forgetting that "and" typically multiplies probabilities for independent events while "or" adds (with overlap subtracted); and confusing permutations (order matters) with combinations (order does not). Also watch for sampling-bias questions-recognize that a voluntary-response or convenience sample may not represent the population. For dependent events, remember to adjust the denominator after a draw without replacement.
Worked example: A bag has 4 red and 6 blue marbles. Probability of drawing two reds without replacement: (4/10)·(3/9) = 12/90 = 2/15. Because the first draw is not replaced, the second probability uses 3 reds out of 9 remaining.
Practice interpreting correlation vs. causation and reading box plots for quartiles and outliers.