Gamma = sum of k iid Exponentials. It generalises the Exponential to 'wait for the k-th event' β the continuous mirror of the Negative Binomial.
β Intro Β· expand
Try first (productive failure)
Before the worked example: spend 60 seconds taking your best shot at this.
A guess is fine β being briefly wrong about a problem makes the explanation
land harder when you read it. This appears once per tutorial; skip
if you already know the trick.
60s
β Try first Β· expand
Worked example
Calls arrive at a service desk as a Poisson process at rate Ξ» = 0.5 per minute. Let T be the time until the 4th call. (a) Identify the distribution of T. (b) Compute E[T] and Var(T). (c) Compute P(T < 8 minutes).
β Worked example Β· expand
Practice 1 of 3Type a fraction, decimal, or expression β mathjs parses it.
β Practice Β· expand
Reflection
Where does this distribution sit in the story chain β what question does it answer that the previous distribution couldn't? Try to recall the key moment formulas (mean, variance) without looking them up.
