Question

A college conducts a common test for all the students. For the Mathematics portion of this test, the scores are normally distributed with a mean of 502 and a standard deviation of 115. Based on this information, what percentage of students would be expected to score between 400 and 590

Answer 1

Using the normal distribution, it is found that 58.97% of students would be expected to score between 400 and 590.

Normal Probability Distribution

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

$Z = \frac{X - \mu}{\sigma}$

• 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 are given, respectively, by:

$\mu = 502, \sigma = 115$

The proportion of students between 400 and 590 is the p-value of Z when X = 590 subtracted by the p-value of Z when X = 400, hence:

X = 590:

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{590 - 502}{115}$

Z = 0.76

Z = 0.76 has a p-value of 0.7764.

X = 400:

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{400 - 502}{115}$

Z = -0.89

Z = -0.89 has a p-value of 0.1867.

0.7764 - 0.1867 = 0.5897 = 58.97%.

58.97% of students would be expected to score between 400 and 590.

More can be learned about the normal distribution at brainly.com/question/27643290

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