Chapter 4: Q.3 (page 282)
Short Answer
The necessary probability is .
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Chapter 4: Q.3 (page 282)
The necessary probability is .
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Use the following information to answer the next eight exercises: The Higher Education Research Institute at UCLA collected data from incoming first-time, full-time freshmen from four-year colleges and universities in theU.S. of those students replied that, yes, they believe that same-sex couples should have the right to legal marital status. Suppose that you randomly pick eight first-time, full-time freshmen from the survey. You are interested in the number that believes that same sex-couples should have the right to legal marital status.
On average how many would you expect to answer yes?
Complete the expected value table.

It has been estimated that only about 30% of California residents have adequate earthquake supplies. Suppose we are interested in the number of California residents we must survey until we find a resident who does not have adequate earthquake supplies.
a. In words, define the random variable X.
b. List the values that X may take on.
c. Give the distribution of X. X ~ _____(_____,_____)
d. What is the probability that we must survey just one or two residents until we find a California resident who does not have adequate earthquake supplies?
e. What is the probability that we must survey at least three California residents until we find a California resident who does not have adequate earthquake supplies?
f. How many California residents do you expect to need to survey until you find a California resident who does not have adequate earthquake supplies?
g. How many California residents do you expect to need to survey until you find a California resident who does have adequate earthquake supplies?
Approximately of students at a local high school participate in after-school sports all four years of high school. A group of seniors is randomly chosen. Of interest is the number that participated in after-school sports all four years of
high school.
a. In words, define the random variable .
b. List the values that may take on.
c. Give the distribution of
d. How many seniors are expected to have participated in after-school sports all four years of high school?
e. Based on numerical values, would you be surprised if none of the seniors participated in after-school sports all
four years of high school.
f. Based on numerical values, is it more likely that four or that five of the seniors participated in after-school sports
all four years of high school? Justify your answer numerically.
According to a recent Pew Research poll, 75% of millenials (people born between 1981 and 1995) have a profile on a social networking site. Let X = the number of millenials you ask until you find a person without a profile on a social networking site.
a. Describe the distribution of X.
b. Find the (i) mean and (ii) standard deviation of X.
c. What is the probability that you must ask ten people to find one person without a social networking site?
d. What is the probability that you must ask 20 people to find one person without a social networking site?
e. What is the probability that you must ask at most five people?
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