Step 1: which distribution fits the exercise?
Uniform
Binomial
Normal
Student t
Chi-square
F
- Uniform: use this when every value between one minimum and one maximum is equally likely. There is no special center and no bell shape, just a flat distribution across the interval.
- Binomial: use this when you repeat the same yes/no trial a fixed number of times and count how many successes happen.
- Normal: use this for a bell-shaped variable measured on a scale, especially when the exercise gives you a mean and a standard deviation.
- Student t: use this when the exercise is about a sample mean and the population standard deviation is unknown, so you work with `s` instead of `σ`.
- Chi-square: use this for variance questions, squared standardized values, or sums of squared normal values. It is only defined for positive x values.
- F: use this when the exercise compares two variances, often with one variance in the numerator and one in the denominator.