Table of contents
- 1. Intro to Stats and Collecting Data55m
- 2. Describing Data with Tables and Graphs1h 55m
- 3. Describing Data Numerically1h 45m
- 4. Probability2h 16m
- 5. Binomial Distribution & Discrete Random Variables2h 33m
- 6. Normal Distribution and Continuous Random Variables1h 38m
- 7. Sampling Distributions & Confidence Intervals: Mean1h 3m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 12m
- 9. Hypothesis Testing for One Sample1h 1m
- 10. Hypothesis Testing for Two Samples2h 8m
- 11. Correlation48m
- 12. Regression1h 4m
- 13. Chi-Square Tests & Goodness of Fit1h 20m
- 14. ANOVA1h 0m
6. Normal Distribution and Continuous Random Variables
Standard Normal Distribution
Problem 5.1.20
Textbook Question
Using and Interpreting Concepts
Finding Area In Exercises 17–22, find the area of the shaded region under the standard normal curve. If convenient, use technology to find the area.


1
Step 1: Understand the problem. The shaded region under the standard normal curve represents the area between z = -0.9 and z = 0. This area corresponds to the probability of a standard normal random variable falling within this range.
Step 2: Recall that the standard normal curve is symmetric about z = 0, and the total area under the curve is 1. The area under the curve between two z-values can be found using the cumulative distribution function (CDF) of the standard normal distribution.
Step 3: Use the standard normal table or technology (such as a graphing calculator or statistical software) to find the cumulative probability for z = -0.9 and z = 0. The cumulative probability for a z-value represents the area under the curve to the left of that z-value.
Step 4: To find the area of the shaded region, subtract the cumulative probability at z = -0.9 from the cumulative probability at z = 0. This gives the area between these two z-values.
Step 5: If using technology, input the z-values into the software or calculator to directly compute the area. Alternatively, use the standard normal table to look up the cumulative probabilities and perform the subtraction manually.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Standard Normal Distribution
The standard normal distribution is a special case of the normal distribution where the mean is 0 and the standard deviation is 1. It is represented by the variable 'Z', which indicates how many standard deviations an element is from the mean. This distribution is symmetric and bell-shaped, making it essential for calculating probabilities and areas under the curve.
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Area Under the Curve
In statistics, the area under the curve (AUC) of a probability distribution represents the probability of a random variable falling within a certain range. For the standard normal distribution, this area can be found using Z-scores and standard normal tables or technology. The shaded region in the graph indicates the probability associated with the Z-scores between -0.9 and 0.
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Z-Score
A Z-score is a statistical measurement that describes a value's relationship to the mean of a group of values. It is calculated by subtracting the mean from the value and then dividing by the standard deviation. Z-scores are crucial for standardizing scores across different distributions, allowing for comparison and the calculation of probabilities using the standard normal distribution.
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