# PracticeS8 Essay

3987 WordsNov 9, 201416 Pages

A) mean, median, SD, correlation, histograms
1) Find the mean, median, SD, IQR for the following data set:
5 5 8 10 12 15 15 19 20 21
What are the values of the SD & IQR ?
2) Find the mean, median, SD & IQR for the data in (1) after it has been transformed as follows: new value = 2.8(old value) – 7.2 Which statement is true ?
a) all four measures change so that new value = 2.8(old value) – 7.2
b) the mean, median & IQR change so that new value = 2.8(old value) – 7.2, but new SD = 2.8(old SD).
c) the mean & median change so that new value = 2.8(old value) – 7.2, but the SD & IQR change so that new value = 2.8(old value)
3) Find the height of the density*…show more content…* What was the average tip charge?
a) $8.75 b) $9.00 c) $9.25 d) $9.75 e) $10.40
(19) In problem (18) suppose the standard deviation of bill amounts was $18. What was the standard deviation of tip sizes?
a) 1.18 b) 1.36 c) 1.54 d) 1.88 e) 2.70
(20) What can you say about the correlation r between heights of husbands & wives?
Bob (height = avr. husband height) Bev (height way above avr. wife height) 0 Joe (much taller than avr. husband) Jen (much shorter than avr. wife) + Lou (height = avr. husband height) Ann (height = avr. wife height) 0 Ted (shorter than avr. husband) Deb (slightly taller than avr. wife) + Gus (much shorter than avr. husb.) Sue (height = avr. wife height) 0
a) r > 0 b) r = 0 c) r < 0 d) any of these could be true.
(21) Which one of the following statements is true about the correlation coefficient, r ? a) r does not depend on the units of measurement (inches, feet, meters, etc.) b) r is not affected by the presence of outliers c) r is always between 0 and 1 d) a high ( + or - ) r is proof of a cause & effect relationship between x & y e) none of the above statements are true
(22) The mean age of the 30 members of the TC Jets is 28. After the current season, five members whose mean age is 35 will retire. They will be replaced by five new members whose mean age is 24. What will the new mean age of the Jets be ? a) 25.88 b) 26.17 c) 26.52 d) 27.12 e) 27.38
B) normal