Calculate mean or variance

A question is this type if and only if it asks to find, state, or prove the mean or variance of an exponential distribution, either from the PDF or using calculus.

1 questions

AQA Further Paper 3 Statistics 2021 June Q7
7 The random variable \(X\) has an exponential distribution with parameter \(\lambda\) 7
  1. Prove that \(\mathrm { E } ( X ) = \frac { 1 } { \lambda }\)
    7
  2. Prove that \(\operatorname { Var } ( X ) = \frac { 1 } { \lambda ^ { 2 } }\)