Market Researchers have become more interested in the potential of social networking sites. But they need to understand the demographics of social networking users. A recent survey showed that 22 of the 30 respondents who reported earning less than $30,000 per year said that they were social networking users. The mean salary of the 22 respondents was $21,500 with a standard deviation of $200. On the other hand, 20 of the 30 respondents who reported earning more than $70,000 per year said that they were social networking users. The mean salary of the 20 respondents was $90,000 with a standard deviation of $300. (a) Is there is enough evidence to infer that those who reported earning less than $30,000 per year are more likely to be social networking users? Assume that the level of significance is 2.5%. (b) Estimate with 98% confidence the variance of salaries of the entire population
Market Researchers have become more interested in the potential of social networking sites. But
they need to understand the demographics of social networking users. A recent survey showed that
22 of the 30 respondents who reported earning less than $30,000 per year said that they were
social networking users. The mean salary of the 22 respondents was $21,500 with a standard
deviation of $200. On the other hand, 20 of the 30 respondents who reported earning more than
$70,000 per year said that they were social networking users. The mean salary of the 20
respondents was $90,000 with a standard deviation of $300.
(a) Is there is enough evidence to infer that those who reported earning less than $30,000 per year
are more likely to be social networking users? Assume that the level of significance is 2.5%.
(b) Estimate with 98% confidence the variance of salaries of the entire population of social network
users earning more than $70,000 per year
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