Pick the best model for each scenario: Uniform, Exponential, Lognormal, Normal, Gamma, Beta, Weibull, or Chi-Square. Click an answer to see feedback. Score updates automatically.
1) Time between random arrivals to a help desk is memoryless.
2) Component lifetimes with an increasing failure rate as they age (wear-out).
3) A proportion/probability that must stay between 0 and 1 (e.g., defect rate).
4) Measurement errors from many tiny independent effects; symmetric around a mean.
5) Positive, right-skewed quantity driven by multiplicative factors (e.g., repair cost).
6) Any value in an interval is equally likely (e.g., random start time in a 10-min window).
7) Waiting time until the k-th random arrival in a Poisson process.
8) Square and sum of k independent standard normals (appears in variance tests).
9) Battery lifetime with a constant hazard rate (memoryless lifetime).
10) Prior for an unknown success probability in a binomial model (Bayesian).
11) Wind speeds: strictly positive, often right-skewed; engineering textbooks favor this model.
12) Part dimensions clustered around a target value with symmetric variability.
13) Model a bounded random setting time for glue that can be anywhere between 30–45 minutes with equal chance.
14) Total waiting time to see k rare events (sum of k independent memoryless waits).
15) Goodness-of-fit and variance tests often rely on this distribution of squared z’s.