contestada

The standard deviation of a sample taken from population A is 17.6 for a sample of 25. The standard deviation of a sample taken from population B is 21.2 for a sample of 30. The standard deviation of the sample mean difference is?

Respuesta :

JcAlmighty
The answer is 5.5

The standard deviation (sd orĀ Ļƒ) of the sample mean difference is:
sd =Ā āˆš(sdā‚Ā²/nā‚ + sdā‚‚Ā²/nā‚‚)

For the population A:
sdā‚ = 17.6
nā‚ = 25

For the population B:
sdā‚‚ = 21.2
nā‚‚ = 30

Hence:
sd =Ā āˆš(sdā‚Ā²/nā‚ + sdā‚‚Ā²/nā‚‚)
Ā  Ā  =Ā āˆš(17.6Ā²/20 + 21.2Ā²/30)
Ā  Ā  =Ā āˆš(309.76/20 + 449.44/30)
Ā  Ā  =Ā āˆš(15.49 + 14.98)
Ā  Ā  =Ā āˆš(30.47)
Ā  Ā  =Ā 5.5

Otras preguntas