sigma=sqrt((N_(1)sigma_(1)^(2)+N_(2)sigma_(2)^(2)+N_(1)d_(1)^(2)+N_(2)d_(2)^(2))/(N_(1)+N_(2))) is the formula of:

sigma=sqrt((N_(1)sigma_(1)^(2)+N_(2)sigma_(2)^(2)+N_(1)d_(1)^(2)+N_(2)

1.	sigma=sqrt((N_(1)sigma_(1)^(2)+N_(2)sigma_(2)^(2)+N_(1)d_(1)^(2)+N_(2)d_(2)^(2))/(N_(1)+N_(2))) is the formula of:
Answer» COMBINED mean DEVIATION combined quartile deviation combined STANDARD deviation coefficient of variation Solution :C