Which Is the Correct Formula for the Proportionate Reduction in Error

Multiple Choice

Which is the correct formula for the proportionate reduction in error?

A) (b) $\frac { \sqrt { S S _ { x } } } { \sqrt { S S _ { y } } }$
B) $\frac { X - M _ { n } } { S D _ { n } }$
C) a + bX
D) $( \operatorname { SStotan } - \mathrm { SSen \sigma } )$
SNtral