Math Problem Statement

Scores for a common standardized college aptitude test are normally distributed with a mean of 506 and a standard deviation of 111. Randomly selected men are given a Test Preparation Course before taking this test. Assume, for sake of argument, that the preparation course has no effect.

If 1 of the men is randomly selected, find the probability that his score is at least 564.7. P(X > 564.7) = Enter your answer as a number accurate to 4 decimal places.

Solution

To solve this problem, we need to calculate the probability that a randomly selected man scores at least 564.7 on a standardized test, assuming the scores follow a normal distribution with a mean (μ\mu) of 506 and a standard deviation (σ\sigma) of 111.

The formula for converting a raw score XX to a standard normal variable ZZ is:

Z=XμσZ = \frac{X - \mu}{\sigma}

Step 1: Calculate the Z-score

Given:

  • X=564.7X = 564.7
  • μ=506\mu = 506
  • σ=111\sigma = 111

Z=564.7506111=58.71110.5288Z = \frac{564.7 - 506}{111} = \frac{58.7}{111} \approx 0.5288

Step 2: Find the probability from the Z-score table

Now, we want to find P(X>564.7)P(X > 564.7), which is equivalent to P(Z>0.5288)P(Z > 0.5288).

Using a standard normal distribution table (or a calculator), we can find the cumulative probability for Z=0.5288Z = 0.5288. The table gives P(Z<0.5288)0.7016P(Z < 0.5288) \approx 0.7016.

Step 3: Calculate the probability

Since we need the probability that ZZ is greater than 0.5288, we subtract the cumulative probability from 1:

P(Z>0.5288)=1P(Z<0.5288)=10.7016=0.2984P(Z > 0.5288) = 1 - P(Z < 0.5288) = 1 - 0.7016 = 0.2984

Thus, the probability that a randomly selected man scores at least 564.7 is approximately 0.2984.


Would you like further clarification or details on this? Here are 5 related questions to expand your understanding:

  1. How would the probability change if the standard deviation was smaller?
  2. What is the probability that a randomly selected man scores less than 400?
  3. How do we calculate the Z-score for any given test score?
  4. What is the significance of using the standard normal distribution for these calculations?
  5. How can you interpret a Z-score of 0.5288 in terms of test performance?

Tip: The Z-score tells you how many standard deviations a value is from the mean, which helps in comparing different distributions.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Probability
Normal Distribution
Z-scores

Formulas

Z = (X - μ) / σ
P(Z > z) = 1 - P(Z < z)

Theorems

Empirical Rule for Normal Distribution

Suitable Grade Level

Grades 11-12