Respuesta :
Answer:
The probability that the student's IQ is at least 140 points is of 55.17%.
Step-by-step explanation:
Problems of normally distributed samples can be 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:
University A: [tex]\mu = 150, \sigma = 77[/tex]
a) Select a student at random from university A. Find the probability that the student's IQ is at least 140 points.
This is 1 subtracted by the pvalue of Z when X = 140. So
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]Z = \frac{140 - 150}{77}[/tex]
[tex]Z = -0.13[/tex]
[tex]Z = -0.13[/tex] has a pvalue of 0.4483.
1 - 0.4483 = 0.5517
The probability that the student's IQ is at least 140 points is of 55.17%.
