The scores for the Algebra 2 CFE are normally distributed with a mean score of 45 and a standard deviation of 5.6. If you score 52 on the test, what percentage of test takers scored lower than you?

87.49 %

89.44 %

90.32 %

91.15%

Respuesta :

Answer:

89.44%

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore 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 pvalue, we get the probability that the value of the measure is greater than X.

In this question:

[tex]\mu = 45, \sigma = 5.6[/tex]

If you score 52 on the test, what percentage of test takers scored lower than you?

This is the pvalue of Z when X = 52.

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

[tex]Z = \frac{52 - 45}{5.6}[/tex]

[tex]Z = 1.25[/tex]

[tex]Z = 1.25[/tex] has a pvalue of 0.8944.

So 89.44% of test takers scored lower than you.

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