A population has a mean of 200 and a standard deviation of 50. Suppose a simple random sample of size 100 is selected and x is used to estimate . a. What is the probability that the sample mean will be within 65 of the population mean

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Answer:

z(195) = (195-200)/50 = -0.1

z(205) = (205-200)/50 = +0.1

P(195 < x < 205) = p(-0.1 < z < 0.1) = 0.0797

Step-by-step explanation:

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Using the normal distribution and the central limit theorem, it is found that there is a 1 = 100% probability that the sample mean will be within 65 of the population mean.

In a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:

[tex]Z = \frac{X - \mu}{\sigma}[/tex]

  • It measures how many standard deviations the measure is from the mean.  
  • After finding the z-score, we look at the z-score table and find the p-value associated with this z-score, which is the percentile of X.
  • By the Central Limit Theorem, the sampling distribution of sample means of size n has standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].

In this problem:

  • The mean is of 200, hence [tex]\mu = 200[/tex].
  • The standard deviation is of 50, hence [tex]\sigma = 50[/tex].
  • The sample size is of 100, hence [tex]n = 100, s = \frac{50}{\sqrt{100}} = 5[/tex].

We want the probability that the sample mean will be within 65 of the population mean, hence:

[tex]Z = \frac{65}{s}[/tex]

[tex]Z = \frac{65}{5}[/tex]

[tex]Z = 13[/tex]

The probability is P(|Z| < 13), which is the p-value of Z = 13 subtracted by the p-value of Z = -13.

Looking at the z-table:

  • Z = 13 has a p-value of 1.
  • Z = -13 has a p-value of 0.

1 - 0 = 1

1 = 100% probability that the sample mean will be within 65 of the population mean.

To learn more about the normal distribution and the central limit theorem, you can take a look at https://brainly.com/question/24663213