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Suppose x has a distribution with = 29 and = 11. (a) If random samples of size n

ID: 3065067 • Letter: S

Question

Suppose x has a distribution with = 29 and = 11.

(a) If random samples of size n = 16 are selected, can we say anything about the x distribution of sample means?

No, the sample size is too small.Yes, the x distribution is normal with mean x = 29 and x = 0.7.     Yes, the x distribution is normal with mean x = 29 and x = 2.75.Yes, the x distribution is normal with mean x = 29 and x = 11.


(b) If the original x distribution is normal, can we say anything about the x distribution of random samples of size 16?

Yes, the x distribution is normal with mean x = 29 and x = 11.Yes, the x distribution is normal with mean x = 29 and x = 2.75.     No, the sample size is too small.Yes, the x distribution is normal with mean x = 29 and x = 0.7.


Find P(25 x 30). (Round your answer to four decimal places.)

Explanation / Answer

The central limit theorem states that the sample mean follows approximately the normal distribution with mean µ and standard deviation /n , where µ and are the mean and standard deviation of the population from where the sample was selected. The sample size n has to be large (usually n 30) if the population from where the sample is taken is non-normal. If the population follows the normal distribution then the sample size n can be either small or large.

a) If random samples of size n = 16 are selected, can we say anything about the x distribution of sample means?

  No, the sample size is too small

b)  If the original x distribution is normal, can we say anything about the x distribution of random samples of size 16?

Standard deviation,

/n=11/16=2.75

Yes, the x distribution is normal with mean x = 29 and x = 2.75.

c) P(25 X 30)

Z=(X- µ)/

Z=(25-29.5)/2.75

Z=-1.45

Z=(30-29.5)/2.75

Z=0.36

  P(25 X 30)=P(-1.45<Z<0.36)

P(-1.45<Z<0.36)=0.6406-0.0735=0.5671

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