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In: Statistics and Probability

A pollster claims that the mean amount spent on Christmas gifts by an American family is...

A pollster claims that the mean amount spent on Christmas gifts by an American family is
$930 with a standard deviation of $180. What is the probability that the mean amount spent on
Christmas gifts for a sample of 500 families is between $910 and $970?

In one city, 85% of eligible voters are registered to vote. If 425 randomly selected
eligible voters are surveyed, what is the probability that at least 82% of those selected are
registered to vote?

A sample of 26 different payroll departments found that the employees worked an
average of 309.7 days a year with a standard deviation of 24.8 days. What is the 99%
confidence interval for the average days worked for all payroll departments?

Out of 180 randomly selected adults in the United States who were surveyed, 74 exercise on a regular basis. Construct a 98% confidence interval for the proportion of all
adults in the United States.

A study of elephants wishes to determine the average weight of a certain subspecies of
elephants. The standard deviation of the population is 1100 pounds. How many elephants
need to be weighed so that we can be 95% confident to be accurate within 130 pounds?

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orchestra answered 1 year ago
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