# STATS Pre Test Paper Problems

August 14, 2017

Name: ___________________________ID#_________________AMS ______Your TA_________________Pre-test Part BThe following is a split stem plot of 52 data points. Legend: stem of 17 and a leaf of 4 =17.4174177 7 7 8 9180 1 2 2 3 3 3 4185 5 9192 3 3 4 4 4195 5 6 6 6 6 6 6 7 7 7 8201 2 3 3 3 3 4207 8210 0 02172212292342351.What is the range and the midrange2.Is this data symmetric, positively skewed or negatively skewed?3.Find the mode, the median, the mean, the standard deviation, the coefficient of variationUse the calculator. (STAT EDIT STAT CALC 1 var stats )4.Find the IQR, lower fence, upper fence, Are there any outliers? If so, please state them.5. True or false?·If every data point in a sample ismultiplied by the constant (-4) to obtain a new data set, the new mean will be (-4)(old mean) and the new std. deviation will now be 4 times as large as the old standard deviation. ·The standard dev is a measure of the variability of the data points from the mean, on average·The variance is an expression of the standard deviation relative to the mean.·If every value of a data set is halved, the variance will be halved as well.·The degrees of freedom when calculating the sample standard deviation is (n-1)·If my data is mound shaped I expect the 98th percentile to lie roughly two standard deviations above the mean6. What do you get when you compute the mean of a dichotomous variable such as On time/Late where late is assigned a “1” and on time is assigned a “0”?7. Are you able to use a weighted average to estimate the population average where Stratified random sampling has been implemented? N = 100 has been separated into 2 strata of sizes 30 and 70. Samples of n1=10 and n2=15 are taken from the 2 strata. The sample average in the first sample is 3 and the sample average of the second sample is 4. Estimate the average of the population. 8. .png”>Find the mean, the total number of observations, the modal class, the standard deviation, the variance.9. .png”>what is your estimate the sample correlation coefficient r? 10..png”>·What is the minimum score required to be in the top 25% of distribution B·Which has a larger variability B or D?·Find the IQR of C·B is ______________skewed·If I needed to convert D to a modified box plot, estimate the upper fence beyond which all values would be outliers.11. I am considering some mutual fund companies for an investment. The one with the lowest coefficient of variation (CV), has the ___________(lowest/highest) volatility, and is the _________(least/most) reliable. 12.What rule would you use for mound shaped data? State the rule.13. What is Chebyshev’s thm?When can you use it? 14. For Right skewed data what is the relationship between the mean, median and mode?15. What is a back to back stem and leaf display used for? 16.Data set Y has been obtained from X by doubling each value in X and adding a constant of 2000 to the result. Is the CV of Y the same as the CV of X?Is the std dev (Y) the same as the standard deviation of X?Is the mean of Y the same as the mean of X?Is the Variance of Y four times the variance of X?17.What kind of distributions do we use the box plot for?18.In the first two years your investment increases by 2.5% annually, in the third year it returns 12% but in the fourth year it goes down 7%. The “average rate of return” is determined using the geometric mean. What is the average annual rate of return over the four years?19.T/F The slope of the least squares line indicates the value of the correlation coefficient, thus a scatter plot with a least squares line with higher slope will have a higher correlation coefficient.20.If the class mean is 30 and the class variance is 4 and Susan scores a 28, what is her z score?21.According to Chebyshev’s theorem, what is the minimum percentage of data within 2.25 standard deviations of the mean?22.To compare the variability of 2 datasets given their box plots side by side, what about the box plots would you look to compare?

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