1. A certain standardized test has scores which range from 0 to 500, with decima

Question

1. A certain standardized test has scores which range from 0 to 500, with decimal scores possible. Scores on the exam are normally distributed with a mean of 308 and a standard deviation of 47.

What proportion of students taking the exam receive a score less than 365?

2. A certain standardized test has scores which range from 0 to 500, with decimal scores possible. Scores on the exam are normally distributed with a mean of 306 and a standard deviation of 48.

What proportion of students taking the exam receive a score greater than 357?

Round your answer to 4 decimal places.

3. A certain standardized test has scores which range from 0 to 500, with decimal scores possible. Scores on the exam are normally distributed with a mean of 311 and a standard deviation of 46.

What proportion of students taking the exam receive a score that is within 78 points of the mean?

Round your answer to 4 decimal places.

4. A certain standardized test has scores which range from 0 to 500, with decimal scores possible. Scores on the exam are normally distributed with a mean of 319 and a standard deviation of 46.

Find the percentile P80 for the scores of students taking the exam.

Round your answer to 2 decimal places.

Explanation / Answer

mean=308

sd=47

P(x<365)=P(z<(365-308)/47)=P(z<1.21)

from normal distribution table, probability = 0.8869

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