Author: chris

statistic

13. Workers Distractions A recent study showed that
the modern working person experiences an average of
2.1 hours per day of distractions (phone calls, e-mails,
impromptu visits, etc.). A random sample of 50 workers
for a large corporation found that these workers were
distracted an average of 1.8 hours per day and the
population standard deviation was 20 minutes. Estimate
the true mean population distraction time with 90%
confidence, and compare your answer to the results of
the study.
Source: Time Almanac.

14. Golf Averages A study of 35 golfers showed that their
average score on a particular course was 92. The
standard deviation of the population is 5.
a. Find the best point estimate of the mean.
b. Find the 95% confidence interval of the mean score
for all golfers.
c. Find the 95% confidence interval of the mean score
if a sample of 60 golfers is used instead of a sample
of 35.
d. Which interval is smaller? Explain why.

17. Television Viewing A study of 415 kindergarten students
showed that they have seen on average 5000 hours of
television. If the sample standard deviation of the
population is 900, find the 95% confidence level of the
mean for all students. If a parent claimed that his children
watched 4000 hours, would the claim be believable?

18. Day Care Tuition A random sample of 50 four-year-olds
attending day care centers provided a yearly tuition
average of $3987 and the population standard deviation
of $630. Find the 90% confidence interval of the true
mean. If a day care center were starting up and wanted to
keep tuition low, what would be a reasonable amount to
charge?

19. Hospital Noise Levels Noise levels at various area
urban hospitals were measured in decibels. The mean
of the noise levels in 84 corridors was 61.2 decibels,
and the standard deviation of the population was 7.9.
Find the 95% confidence interval of the true mean.
Source: M. Bayo, A. Garcia, and A. Garcia, Noise Levels in an Urban
Hospital and Workers Subjective Responses, Archives of Environmental
Health 50, no. 3, p. 249 (MayJune 1995). Reprinted with permission of
the Helen Dwight Reid Educational Foundation. Published by Heldref
Publications, 1319 Eighteenth St. N.W., Washington, D.C. 20036-1802.
Copyright 1995.

20. Length of Growing Seasons The growing seasons for
a random sample of 35 U.S. cities were recorded,
yielding a sample mean of 190.7 days and the population
standard deviation of 54.2 days. Estimate the true mean
population of the growing season with 95% confidence

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Global Warming

Read the Case study, which is below, and answer the questions that will be provided below.

Case 1.4: Getting Warmer?
In 2012 sixteen notable scientists published an opinion piece claiming that there is \”no need to panic about global warming\” and \”there\’s no compelling scientific argument for drastic action to \’decarbonize\’ the world\’s economy\” (Allegre et al., 2012). This flew in the face of conventional wisdom and many scientific articles to the contrary (see Lavell, 2008; Farnsworth & Lichter, 2011; Oreskes, 2004). The sixteen scientists were widely representative academically (MIT, Princeton University, Cambridge University, and the University of Paris), professionally (American Physical Society, The National Academy of Engineering, The National Academy of Sciences, and the World Federation of Scientists), and globally (United States, Europe, The Middle East, and Australia). Since the mid-twentieth century there was growing public consensus of experts and nonexperts that anthropogenic (human-caused) climate change was real and dangerous. The American Physical Society had recently summed up the position thus: \”\’The evidence is incontrovertible: Global warming is occurring. If no mitigating actions are taken, significant disruptions in the Earth\’s physical and ecological systems, social systems, security, and human health are likely to occur. We must reduce emissions of greenhouse gases beginning now\” (Allegre et al., 2012). Allegre et al. (2012), including Roger Cohen, a fellow of the American Physical Society, deny that such evidence is incontrovertible and argue that the evidence suggests the contrary: The earth is not getting warmer and carbon dioxide, a major greenhouse gas, is not a pollutant. They suggest that a major reason for denying this is financial: \”alarmism over climate is of great benefit to many, providing government funding for academic research and a reason for government bureaucracies to grow. Alarmism also offers an excuse for governments to raise taxes, taxpayer-funded subsidies for businesses that understand how to work the political system, and a lure for big donations to charitable foundations promising to save the planet.\”
Moreover, Allegre et al. (2012) claim that it would make better economic sense to remove greenhouse gas controls, especially for \”the less-developed parts of the world that would like to share some of the same advantages of material well-being, health and life expectancy that the fully developed parts of the world enjoy now.\” While this might lead to increased carbon monoxide and \”modest warming,\” Allegre et al. (2012) believe this \”will be an overall benefit to the planet.\”