If $X _ { 1 } \text { and } X _ { 2 }$

Short Answer

If $X _ { 1 } \text { and } X _ { 2 }$ are independent __________ random variables with $v _ { 1 } \text { and } v _ { 2 }$ degrees of freedom respectively, then the random variable $F = \left( X _ { 1 } / v _ { 1 } \right) / \left( X _ { 2 } / v _ { 2 } \right)$ has an F distribution.