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Assume that the random variable X is normally​ distributed, with mean and standard deviation . Compute the probability. Be sure to draw a normal curve with the area corresponding to the probability shaded.

Assume that the random variable X is normally distributed with mean and standard deviation Compute the probability Be sure to draw a normal curve with the area class=

Respuesta :

Using the normal distribution, the probability that x is of at most 40, represented by option B, is given as follows:

[tex]P(X \leq 40) = 0.1587[/tex]

Normal Probability Distribution

The z-score of a measure X of a normally distributed variable with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex] is given by:

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

  • The z-score measures how many standard deviations the measure is above or below the mean.
  • Looking at the z-score table, the p-value associated with this z-score is found, which is the percentile of X.

The mean and the standard deviation of the distribution are given, respectively, by:

[tex]\mu = 51, \sigma = 11[/tex]

The probability that x is of at most 40 is the p-value of Z when X = 40, hence:

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

[tex]Z = \frac{40 - 51}{11}[/tex]

Z = -1

Z = -1 has a p-value of 0.1587.

Hence the probability is:

[tex]P(X \leq 40) = 0.1587[/tex]

Which is the part to the left of X = 40 of the distribution, hence option B is correct.

More can be learned about the normal distribution at https://brainly.com/question/28135235

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