Assume that adults have IQ scores that are normally distributed with a mean of 101.5 and a standard deviation 24.3. Find the first quartile Q,, which is the IQ score separating the bottom 25% from the top 75%. (Hint: Draw a graph.) The first quartile is (Type an integer or decimal rounded to one decimal place as needed.)

MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
icon
Related questions
Question
**Understanding Quartiles in a Normal Distribution**

Assume that adults have IQ scores that are normally distributed with a mean of 101.5 and a standard deviation of 24.3. We want to find the first quartile \( Q_1 \), which is the IQ score separating the bottom 25% from the top 75%.

The first quartile is represented by a specific value on the IQ scale. In a normal distribution, this can be found using statistical methods or software that handles standard normal distribution calculations.

**Steps to Find the First Quartile:**

1. **Draw a Normal Distribution Graph**: Visualize or draw a bell curve depicting the normal distribution with mean 101.5. The x-axis represents IQ scores.

2. **Locate \( Q_1 \)**: The first quartile is the point on the x-axis where 25% of the data lies to the left. Graphing this can help illustrate how data is distributed.

3. **Calculate \( Q_1 \)** using the formula for the z-score:
   \[
   Q_1 = \mu + z \times \sigma
   \]
   where \( \mu = 101.5 \) (the mean), \( \sigma = 24.3 \) (the standard deviation), and \( z \) is the z-score associated with the first quartile in a standard normal distribution (approximately -0.674).

4. **Result Interpretation**: Once calculated, \( Q_1 \) will give the IQ score below which 25% of adult IQ scores may be expected to fall.

**The first quartile is:**  \(\_\_\_\)  
(Type an integer or decimal rounded to one decimal place as needed.)

This exercise illustrates how quartiles are used to interpret data distribution, particularly in understanding how scores compare within a population.
Transcribed Image Text:**Understanding Quartiles in a Normal Distribution** Assume that adults have IQ scores that are normally distributed with a mean of 101.5 and a standard deviation of 24.3. We want to find the first quartile \( Q_1 \), which is the IQ score separating the bottom 25% from the top 75%. The first quartile is represented by a specific value on the IQ scale. In a normal distribution, this can be found using statistical methods or software that handles standard normal distribution calculations. **Steps to Find the First Quartile:** 1. **Draw a Normal Distribution Graph**: Visualize or draw a bell curve depicting the normal distribution with mean 101.5. The x-axis represents IQ scores. 2. **Locate \( Q_1 \)**: The first quartile is the point on the x-axis where 25% of the data lies to the left. Graphing this can help illustrate how data is distributed. 3. **Calculate \( Q_1 \)** using the formula for the z-score: \[ Q_1 = \mu + z \times \sigma \] where \( \mu = 101.5 \) (the mean), \( \sigma = 24.3 \) (the standard deviation), and \( z \) is the z-score associated with the first quartile in a standard normal distribution (approximately -0.674). 4. **Result Interpretation**: Once calculated, \( Q_1 \) will give the IQ score below which 25% of adult IQ scores may be expected to fall. **The first quartile is:** \(\_\_\_\) (Type an integer or decimal rounded to one decimal place as needed.) This exercise illustrates how quartiles are used to interpret data distribution, particularly in understanding how scores compare within a population.
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 2 steps with 15 images

Blurred answer
Knowledge Booster
Basics of Inferential Statistics
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, statistics and related others by exploring similar questions and additional content below.
Similar questions
  • SEE MORE QUESTIONS
Recommended textbooks for you
MATLAB: An Introduction with Applications
MATLAB: An Introduction with Applications
Statistics
ISBN:
9781119256830
Author:
Amos Gilat
Publisher:
John Wiley & Sons Inc
Probability and Statistics for Engineering and th…
Probability and Statistics for Engineering and th…
Statistics
ISBN:
9781305251809
Author:
Jay L. Devore
Publisher:
Cengage Learning
Statistics for The Behavioral Sciences (MindTap C…
Statistics for The Behavioral Sciences (MindTap C…
Statistics
ISBN:
9781305504912
Author:
Frederick J Gravetter, Larry B. Wallnau
Publisher:
Cengage Learning
Elementary Statistics: Picturing the World (7th E…
Elementary Statistics: Picturing the World (7th E…
Statistics
ISBN:
9780134683416
Author:
Ron Larson, Betsy Farber
Publisher:
PEARSON
The Basic Practice of Statistics
The Basic Practice of Statistics
Statistics
ISBN:
9781319042578
Author:
David S. Moore, William I. Notz, Michael A. Fligner
Publisher:
W. H. Freeman
Introduction to the Practice of Statistics
Introduction to the Practice of Statistics
Statistics
ISBN:
9781319013387
Author:
David S. Moore, George P. McCabe, Bruce A. Craig
Publisher:
W. H. Freeman