Math Problem Statement

Given that z is a standard normal random variable, find z for each situation (round your answers to two decimal places).

Solution

To solve these questions, I’ll provide the calculations for the missing values using the standard normal distribution (z-scores).

Here's how to approach each part:

  1. (a) Given Area to the left of z=0.9750\text{Area to the left of } z = 0.9750

    • The z-score for an area of 0.9750 is approximately 1.96, which you already have correct.
  2. (b) Given Area between 0 and z=0.4750\text{Area between } 0 \text{ and } z = 0.4750

    • The area between 0 and z being 0.4750 implies that the area to the left of z is 0.5+0.4750=0.97500.5 + 0.4750 = 0.9750.
    • For an area of 0.9750 to the left, the corresponding z-score is 1.96.
  3. (c) Given Area to the left of z=0.7357\text{Area to the left of } z = 0.7357

    • The z-score for an area of 0.7357 is approximately 0.63, which is marked correct.
  4. (d) Given Area to the right of z=0.1251\text{Area to the right of } z = 0.1251

    • Area to the right of z being 0.1251 implies the area to the left is 10.1251=0.87491 - 0.1251 = 0.8749.
    • The z-score for an area of 0.8749 to the left is approximately 1.15.
  5. (e) Given Area to the left of z=0.6293\text{Area to the left of } z = 0.6293

    • The z-score for an area of 0.6293 is approximately 0.33.
  6. (f) Given Area to the right of z=0.3707\text{Area to the right of } z = 0.3707

    • Area to the right of z being 0.3707 implies the area to the left is 10.3707=0.62931 - 0.3707 = 0.6293.
    • The z-score for an area of 0.6293 to the left is approximately 0.33.

Summary of Correct Answers

  • (a) 1.96
  • (b) 1.96
  • (c) 0.63
  • (d) 1.15
  • (e) 0.33
  • (f) 0.33

Would you like further explanation on any part?

Related Questions to Explore:

  1. What is the significance of z-scores in statistics?
  2. How do you interpret areas under the standard normal curve?
  3. What are common z-scores and their corresponding areas?
  4. How would you use z-scores in hypothesis testing?
  5. Can z-scores be negative, and what does a negative z-score mean?

Tip:

When working with z-scores, always double-check the area to ensure if it's to the left or right of the z-score, as this changes the interpretation.

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Math Problem Analysis

Mathematical Concepts

Statistics
Standard Normal Distribution
z-scores
Probability

Formulas

z-score formula
Inverse normal distribution

Theorems

Standard Normal Distribution Curve

Suitable Grade Level

College Statistics or AP Statistics