The time taken to prepare the envelopes to mail a weekly report to all executives in a company has a normal distribution, with a mean of 35 minutes and a standard deviation of 2 minutes. On 95% of occasions the mailing preparation takes less than how many minutes? invN(.95,35,2) -Lower fence of box-plot= Q1-1.5IQR a population has a normal distribution with a mean of 80 and a standard deviation of 3. Q1=invN(.25,80,3)
When drawing a histogram, it is important to label the vertical axis so the reader can determine the counts or percent in each class interval.
A set of data has a median that is much larger than the mean. Which of the following statements is most consistent with this information? A stemplot of the data is skewed left.
A reporter wishes to portray baseball players as overpaid. Which measure of center should he report as the average salary of major league players? The mean
A normal density curve is symmetric, has a peak centered above the mean and the spread of the curve is proportional to the standard deviation
The least-squares regression line is the line that makes the square of the correlation in the data as large as possible. the line that makes the sum of the squares of the vertical distances of the data points from the line as small as possible, and the line that best splits the data in half, with half of the points above the line and half below the line.
There is a strong positive correlation between years of education and income for economists employed by business firms. In particular, economists with doctorates earn more than economists with only a bachelor's degree. There is also a strong positive correlation between years of education and income for economists employed by colleges and universities. But when all economists are considered, there is a negative correlation between education and income. What is this phenomenon called? Simpson’s Paradox
Suppose the actual proportion of undergraduates at Johns Hopkins University who feel drinking is a problem among college students is 70%. In repeated simple random samples of 50 Johns Hopkins undergraduates
_0.7_What is the mean of the sampling distribution of the percentage that feel drinking is a problem?
_0.0648What is the standard deviation of the sampling distribution of the percentage that feel drinking is a problem?sqrt(pq/n); ncdf(37/50,42/50,.7,.0648); ncdf(0,.5,.7, .0648)
_0.2532What is the probability that, in a sample of 50, between 37 and 42 will believe that drinking is a problem?
_0.0010What is the probability that, in a sample of 50, less than 50% will believe that drinking is a problem?
The probability density of a random variable X probability that X is between 0.35 and 1.5= .575 probability that X is at least 1.1. =.45 u=$939. σ = $245. What is the probability that a SRS of 50 automobile insurance policies will have a sample mean within $25 of the population mean? Ncdf(914,964,939,245/sqrt(50)); ncdf(1000,1E99,939,245/sqrt(50))
If a SRS of 50 insurance policies is taken, what is the probability that the sample mean is greater than $1000?
Laboratory data show that the time required to complete two chemical reactions in a production process varies. The first reaction (X) has a mean time of 40 minutes and a standard deviation of 2 minutes; the second (Y) has a mean time of 25 minutes and a standard deviation of 1 minute. The two reactions are run in sequence during production. There is a fixed period of 5 minutes between them as the product of the first reaction is pumped into the vessel where the second reaction will take place. What is the mean time required for the entire process (That is, what is µX+Y+5)? 40+25+5=70
__2.236Find the standard deviation of the entire process assuming that the study shows the two times to be independent. Sqrt(ox2+oy2)=sqrt(22+12)=2.236;