Juan took a Statistics exam and earned a 90%. If the exam scores are normally distributed...

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Juan took a Statistics exam and earned a 90%. If the exam scores are normally distributed with a mean = 75% and SD = 10%, what is Juan's z score?

Based on his z score, what percentage of students scored below Juan?

What is the probability of randomly selecting a student who scored below Juan?

math Statistics-And-Probability

Answer 1

Answer #1

Solution :

z score = (x - ) /

= (90% - 75%) / 10%

= 1.5

Juan's z score = 1.5

P(z < 1.5) = 0.9332 = 93.32%

Answer = 93.32%

Probability = 0.9332

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Answer 2

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