Respuesta :
Answer:
272 is the test score for Brandi.
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.
Mean of 250 and standard deviation of 25:
This means that [tex]\mu = 250, \sigma = 25[/tex]
Brandi scored at the 81st percentile on this test. What was her test score?
The z-score of her score of X has a p-value of 0.81. This means that her score is given by X when Z = 0.88.
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]0.88 = \frac{X - 250}{25}[/tex]
[tex]X - 250 = 0.88*25[/tex]
[tex]X = 272[/tex]
272 is the test score for Brandi.
