Ch. 6 REFERENCES 191 



14. You are given the following hypothetical data from an experimental study 

 of the average daily gains (in pounds) of two groups of 10 steers each: 



For group A: xa = 2.35, s 2 a = 12. 

 For group B: x B = 1.75, 2z 2 B = 180. 



Is the difference in mean average daily gain, d = 0.60 pound, beyond the bounds 

 of reasonable sampling variation; that is, is it statistically significant? 



Ans. t = 0.34; 18 D/F, P S .63; accept H On = m). 



15. Suppose that you have taken the bid in a bridge game and that you and 

 your partner have all the trumps but J, 10, 7, 4, and 3. Before you have led 

 at all, what do you compute as the probability that you would get all the 

 trumps out within 3 leads? 



16. Suppose that you have been told that when 6 unbiased coins were tossed 

 at least 3 of them showed heads. What is the probability that exactly 4 of the 

 coins turned up heads. Ans. P(r — 4 heads) = 15/42. 



17. Suppose that a large jug contains the following numbers of each de- 

 nomination of paper currency, and that you are to withdraw a bill without look- 

 ing and keep it: 50 one-dollar bills, 25 five-dollar bills, 10 ten-dollar bills, 5 

 twenty-dollar bills, 2 fifty-dollar bills, and 1 one-hundred-dollar bill. What is 

 your mathematical expectation on such a game? 



18. If 2 cards are drawn simultaneously from a bridge deck, what is the 

 probability that one will be a spade, the other a heart? Ans. 13/102. 



REFERENCES 



Dixon, Wilfrid J., and Frank J. Massey, Jr., Introduction to Statistical Analysis, 

 McGraw-Hill Book Company, New York, 1951. 



Hald, A., Statistical Theory with Engineering Applications, John Wiley and Sons, 

 New York, 1952. 



Neyman, Jerzy, First Course in Probability and Statistics, Henry Holt and Com- 

 pany, New York, 1950. 



Snedecor, George W., Statistical Methods Applied to Experiments in Agriculture 

 and Biology, Fourth Edition, Iowa State College Press, Ames, Iowa, 1946. 



