 
Summary: Math 140
Introductory Statistics
Professor Bernardo Ábrego
Lecture 21
Sections 8.1
Discussion: Confidence Intervals
D3. According to the 2000 U.S. Census, about 60% of Hispanics
in the United States are of Mexican origin. Would it be
reasonably likely in a survey of 40 randomly chosen Hispanics
to find that 27 are of Mexican origin?
Source: www.census.gov/prod/2001pubs/c2kbr013.pdf.
D4. According to the 2000 U.S. Census, about 30% of people
over age 85 are men. In a random sample of 40 people over age
85, would it be reasonably likely to get 60% who are men?
Source: www.census.gov/prod/2001pubs/c2kbr0110.pdf.
D5. Suppose that in a random sample of 40 toddlers, 34 know
what color Elmo is. What is the 95% confidence interval for the
percentage of toddlers who know what color Elmo is?
D6. Polls usually report a margin of error. Suppose a poll of 40
randomly selected statistics majors finds that 20 are female. The
