Statistics in a Modern World 800
Solutions to Practice Exam 3

  1. 1-.3=.7
  2.  
    1. yes; you can be male or female but not both
    2. yes; .6*.5=.3
    3. .6+.5-.3=.8
    4. 1-.8=.2
  3.  
    1. (a) 1/2
    2. (ii) gambler's fallacy
  4.  
    1. (a) 1/4 * 1/4 = 1/16
    2. (ii) independent
  5.  
    1. 5/6 * 5/6 = 25/36=.69
    2. 1 - 25/36 = 11/36 = .31
    3. (i) relative frequency
  6. 1(.1)+2(.5)+3(.3)+4(.1)=2.4
  7. (c)
  8. (v) optimism
  9. (a) anchoring
  10. (b) second is different from the first and third is different from both of them
  11. (c) this is the opposite of #10
  12. (g) conservatism
  13. (g) pseudo-certainty effect
  14. (a) (more general)
  15. (d) representativeness
  16. (c)
  17. (b)
  18.  
    1. first branch-off: spy or not spy, with probabilities .001 and .999; second branch-off: incriminated or not, with probabilities .8 and .2 for the spies, .16 and .84 for the non-spies
    2. .001(.8)=.0008
    3. .999(.16)=.15984
    4. .0008+.15984=.16064
    5. .0008/.16064=.00498
    6. (d) confusion of the inverse


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