miniproject9 - it very hard to give up their television(c...

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Mini-project 9 1. A credit card company wants to determine the average amount their customers spend per month. They would like to have a margin of error of \$200 for a 95% conﬁdence interval. Past data suggest that the population standard deviation is \$1000. How many customers should the company survey? 2. Which would be hardest for you to give up: your computer or your television? In a recent survey of 1677 college students, 74% of them say their computer would be very hard to give up. Only 48% say their television would be very hard to give up. (a) Develop a 95% conﬁdence interval for the proportion who would ﬁnd it very hard to give up their computer. (b) Develop a 95% conﬁdence interval for the proportion who would ﬁnd
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Unformatted text preview: it very hard to give up their television. (c) Can you conclude that a higher proportion would ﬁnd it diﬃcult to give up their computer than their television? Why or why not? 3. A state’s environmental agency worries that a large percentage of cars may be violating clean air emissions standards. The agency hopes to check a sample of vehicles in order to estimate the proportion violating the standards with a margin of error of 0.03 with 90% conﬁdence. A pilot study suggested that this proportion was 0.15. How many cars should be sampled for a full investigation? 1...
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