Definitions
In the 2008 New Hampton Democratic primary 30% of voters in a CNN poll said they would vote for Hillary Clinton. Surprisingly, in the primary itself, 39% voted for Clinton. The number 39% is a
parameter
A sampling distribution of the means of all possible samples of size 100 is formed. The parent population has a M=5 and standard deviation = 1.5. What is the value of M x-bar?
5
If a true proportion is 0.03 of 240 selected residents. What is the probability that p is more than 0.054?
0.0146
When 319 college students are randomly selected and surveyed, it is found that 120 own a car. Find a 99% confidence interval for the true proportion of all college students who own a car.
(0.31, 0.45)
The variability of a statistic is described by
the spread of its sampling distribution
A 2010 study of 240 randomly selected residents of a subtropical resort city with 82,000 residents found that 5.4% of them had been exposed to the mosquito - borne virus that causes Dengue fever. Suppose the actual percentage of people in the city who have been exposed to the virus is 3%. let p = proportion of residents who have been exposed in a random sample of 240. What is standard deviation ?
A college basketball player makes 80% of his free throws. Over the course of the season she will attempt 100 free throws. Assuming free throw attempts are independent, the probability that the number of free throws she makes exceeds 80 is approximately...
0.5000
To estimate m, the mean salary of full professors at american colleges and universities you obtain the salaries of a random sample of 400 full professors, the sample mean is x-bar = 73,220 and the sample standard deviation is s = 4400. Construct a 99% interval
($72,653 , $73, 787)
A survey conducted by Black Flag asked whether or not the action of a certain type of roach disk was effective in killing roaches. 79% of the respondents agreed that the roach was effective. The number 79% is a
statistic
What condition has to be met for standard deviation calculations?
n < 0.10N
A factory produces plate glass with a mean thickness of 4 mm and a standard deviation of 1.1 mm. A simple random sample of 100 sheets of glass is to be measured, and the sample mean thickness of the 100 sheets x-bar is to be computed. Whaty is the probability that the average thickness x-bar of the 100 sheets is less than 4.1 mm?
0.8183
0.64 /- 0.094
A polling organization announces that the proportion of American voters who favor congressional term limits is 64 percent, with a 95% confidence margin of error of 3 percent. If the opinion poll had announced the margin of error of 80% confidence rather than 95%, this margin of error would....
become more narrow due to decreased confidence
Suppose you are going to roll a 10-sided die 50 times and record p, the proportion of times that the roll is 3 or lower. Find mean and standard deviation
M = 0.3, SD = 0.0648
The incomes in a certain large population of college teachers have a normal distribution with mean $60000 and standard deviation $5,000. Four teachers are selected at random from this population to serve on a salary review committee. What is the probability that their average salary exceeds $65,000?
0.0228
550 +/- 173.88
A political candidate is told by hum polling organization that a 90% confidence interval for the proportion of voters who support his candidacy is 0.45 to 0.53. What are the point estimate and margin of error for this interval?
P = 0.49, M = 0.04
An automobile insurer has found that the repair claims have a mean of $920 and standard deviation of $870. Suppose that the next 100 claims can be regarded as a random sample from the long-run claim process. Find mean and standard deviation.
M = $920, SD = $87
Suppose that 35% of all business executives are willing to switch companies if offered a higher salary. If a headhunter randomly contacts an SRS of 100 executives, what is the probability that over 40% will be willing to switch companies if offered a higher salary?
0.1488
The heights of young American women, in inches, are approximately Normally distributed with mean m and standard deviation s = 2.4. If you want to construct a 95% confidence interval with margin of error of no more than ± 1 inch, the smallest sample I can take is closest to…
23