According to a study, 20% of adults in the United States do not use the Internet. Suppose that 10 adults in the United States are selected randomly. 1) What is the expected number of adults do not use the Internet? 2) What is the probability that 3 of the adults do not use the Internet? 3) What is the probability that at most 3 of the adults do not use the Internet?
Added by Brett F.
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Given that the success rate is 0.2 and the sample size is 10, we can use the formula for expected value: \[ E(X) = n \times p \] \[ E(X) = 10 \times 0.2 = 2 \] Show more…
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David N.
According to a study, 15% of adults in the United States do not use the Internet. Suppose 10 adults in the United States are selected randomly. a. (10 points) Is the selection of the 10 adults a binomial experiment? Explain. b. (10 points) What is the probability that none of the adults use the Internet? c. (10 points) What is the probability that 1 of the adults uses the Internet? d. (10 points) What is the probability that 3 of the adults use the Internet?
Supreeta N.
The increase in Internet usage over the past few years has been phenomenal, as demonstrated by the February 2004 report from the Pew Internet \& American Life Project. The survey of Americans 65 or older (about 8 million adults) reported that $22 \%$ have access to the Internet. By contrast, $58 \%$ of 50 to 64 -year-olds, $75 \%$ of 30 - to 49 -year-olds, and $77 \%$ of 18 - to 29 -year-olds currently go online. Suppose that 50 adults in each age group are to be interviewed. a. What is the probability that "have Internet access" is the response of 10 to 20 adults in the 65 or older group? b. What is the probability that "have Internet access" is the response of 30 to 40 adults in the 50 - to 64-year-old group? c. What is the probability that "have Internet access" is the response of 30 to 40 adults in the 30 - to 49-year-old group? d. What is the probability that "have Internet access" is the response of 30 to 40 adults in the 18 - to 29-year-old group? e. Why are the answers for parts a and d nearly the same? Explain. f. What effect did the various values of $p$ have on the probabilities? Explain.
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