When comparing the means of two populations, it is necessary to assume that their variances are equal and that both populations are normal. TRUE/FALSe.. its statistics

Question

anonymous · Answer

false

anonymous · Answer

thankyou, but would you be able to explain why? =]

anonymous · Answer

If both populations are at least approximately normal and/or you have sufficiently large samples, then you can use a combined variance from the two populations of 
$$σ_z^2=σ_x^2+σ_y^2$$

anonymous · Answer

Maybe review 'Central Limit Theorem' for more details.