Jackson is interested in the number of memories people can recall. He knows that the number of memories recalled is normally distributed in the general population, with a population mean of 30 and a population standard deviation of 5. What is the probability that Jackson randomly selects a person from this population who recalls between 26 and 29 memories

Respuesta :

Answer:

0.2088 = 20.88% probability that Jackson randomly selects a person from this population who recalls between 26 and 29 memories.

Step-by-step explanation:

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set 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]

The Z-score 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. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

Population mean of 30 and a population standard deviation of 5.

This means that [tex]\mu = 30, \sigma = 5[/tex]

What is the probability that Jackson randomly selects a person from this population who recalls between 26 and 29 memories?

This is the pvalue of Z when X = 29 subtracted by the pvalue of Z when X = 26. So

X = 29

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

[tex]Z = \frac{29 - 30}{5}[/tex]

[tex]Z = -0.2[/tex]

[tex]Z = -0.2[/tex] has a pvalue of 0.4207

X = 26

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

[tex]Z = \frac{26 - 30}{5}[/tex]

[tex]Z = -0.8[/tex]

[tex]Z = -0.8[/tex] has a pvalue of 0.2119

0.4207 - 0.2119 = 0.2088

0.2088 = 20.88% probability that Jackson randomly selects a person from this population who recalls between 26 and 29 memories.