In an approximately normal distribution, roughly what share of observations falls within one standard deviation of the mean?
Correct Answer
B) About 68 percent of the observations
Why this is correct: In statistics, for a normal (bell-shaped) distribution, approximately 68% of the observations fall within one standard deviation (plus or minus) of the mean. This is known as the empirical rule. Why the other choices are wrong: "About 50 percent of the observations" is wrong; that's roughly the share within half a standard deviation. "About 95 percent of the observations" is wrong; that's the share within two standard deviations. "About 99 percent of the observations" is wrong; that's roughly the share within three standard deviations. Exam tip: Memorize the 68-95-99 rule for normal distributions: 1, 2, and 3 standard deviations from the mean.
Why This Is the Correct Answer
Why this is correct: In statistics, for a normal (bell-shaped) distribution, approximately 68% of the observations fall within one standard deviation (plus or minus) of the mean. This is known as the empirical rule. Why the other choices are wrong: "About 50 percent of the observations" is wrong; that's roughly the share within half a standard deviation. "About 95 percent of the observations" is wrong; that's the share within two standard deviations. "About 99 percent of the observations" is wrong; that's roughly the share within three standard deviations. Exam tip: Memorize the 68-95-99 rule for normal distributions: 1, 2, and 3 standard deviations from the mean.
More Statistics Questions
A set of comparable sales has a mean of $250,000 and a standard deviation of $20,000. What is the coefficient of variation?
A property sold for $400,000 and resold three years later for $463,050 with no physical change. What compound annual rate does this indicate?
A histogram of neighborhood sale prices shows two distinct peaks. What does this most likely mean?
What does it mean to validate a regression model?
In a market study, what does a frequency distribution of sale prices show?
An appraiser includes months elapsed since each sale as a variable in a price model. What is this intended to capture?
An appraiser presents a statistical analysis in a report. What must accompany it for the reader to weigh it?
An R-squared of 0.86 in a sales model indicates that:
Which measure would best summarize the most common lot size in a subdivision?
Paired sales analysis and regression differ mainly in that regression:
People Also Study
Real Estate Market
13.6% of exam
Property Description
11.8% of exam
Land or Site Valuation
4.5% of exam
Sales Comparison Approach
16.4% of exam
Cost Approach
13.6% of exam