Math Problem Statement

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 50.

What proportion of students taking the exam receive a score less than 366?

Round your answer to four (4) decimal places. (e.g.  0.1234)

Solution

To find the proportion of students who receive a score less than 366, we need to use the properties of the normal distribution.

Step 1: Standardize the score using the Z-score formula

The Z-score tells us how many standard deviations a score is away from the mean. The formula for the Z-score is:

Z=XμσZ = \frac{X - \mu}{\sigma}

Where:

  • X=366X = 366 (the score we are interested in)
  • μ=308\mu = 308 (the mean score)
  • σ=50\sigma = 50 (the standard deviation)

Substituting the values:

Z=36630850=5850=1.16Z = \frac{366 - 308}{50} = \frac{58}{50} = 1.16

Step 2: Find the cumulative probability for Z = 1.16

Now, we need to look up the cumulative probability for Z=1.16Z = 1.16 in the standard normal distribution table or use a calculator that provides the cumulative probability.

For Z=1.16Z = 1.16, the cumulative probability is approximately 0.8770.

Step 3: Conclusion

The proportion of students who score less than 366 is approximately 0.8770.

So, the answer is: 0.8770\boxed{0.8770}

Let me know if you need further explanation or if you'd like to explore more! Here are some related questions:

  1. How would you find the proportion of students scoring above 366?
  2. What happens if the distribution is not normal?
  3. How can you use Z-scores to compare scores from different exams?
  4. What is the proportion of students scoring between 308 and 366?
  5. How would you find the score corresponding to a certain percentile?

Tip: If you ever need to find a percentile for a Z-score, simply look up the Z-score in the standard normal table or use a cumulative probability calculator.

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Math Problem Analysis

Mathematical Concepts

Statistics
Normal Distribution
Probability

Formulas

Z-score formula: Z = (X - μ) / σ
Cumulative probability from standard normal distribution table

Theorems

Empirical Rule
Properties of Normal Distribution

Suitable Grade Level

Grades 10-12, College Level Statistics