In 2017, 1,764,865 students took the SAT exam. The distribution of scores in the verbal section of the SAT had a mean µ = 467 and a standard deviation σ = 111. Let X = a SAT exam verbal section score in 2017. Then X ~ N(467, 111). Find the z-scores for x1 = 235 and x2 = 368.

Respuesta :

Answer:

X1 zscore

[tex]Z = -2.09[/tex]

X2 zscore

[tex]Z = -0.89[/tex]

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 problem, we have that:

[tex]\mu = 467, \sigma = 111[/tex]

x1 = 235

Z when [tex]X = 235[/tex]

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

[tex]Z = \frac{235 - 467}{111}[/tex]

[tex]Z = -2.09[/tex]

x2 = 368.

Z when [tex]X = 368[/tex]

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

[tex]Z = \frac{368 - 467}{111}[/tex]

[tex]Z = -0.89[/tex]