Statistics

Problem Statement for "Conditional"

Problem Statement

Conditional probability can be illustrated with dice problems. What is the probability that you rolled a 12 on a pair of normal 6-sided dice, given that at least one of the dice shows a 6? This is the same question as the following: roll a pair of dice until at least one of the dice shows 6 -- what is the probability that your final roll has 6 on BOTH dice. The surprising answer is 1/11 since of the 36 equally likely rolls, 11 have at least one 6 and 1 of these 11 has 6 on both dice.

Our goal is to solve a generalized version of this problem in which we roll nDice identical dice, each with sides labelled 1,2,...,maxSide. We want to know the probability that the sum of the dice is greater than or equal to theSum given that at least one of the dice shows the value v. Create a class Conditional that contains a method probability that is given nDice,maxSide, v, and theSum and that returns the desired conditional probability.

Definition

Class:
Conditional
Method:
probability
Parameters:
int, int, int, int
Returns:
double
Method signature:
double probability(int nDice, int maxSide, int v, int theSum)
(be sure your method is public)

Notes

  • The returned value must be accurate to within a relative or absolute value of 1E-9.

Constraints

  • nDice and maxSide will be between 1 and 50, inclusive.
  • v will be between 1 and maxSide, inclusive.
  • theSum will be between 1 and maxSide*nDice, inclusive.

Examples

  1. 2

    6

    6

    12

    Returns: 0.09090909090909091

    This is the example above whose answer is 1/11. (Of course, the sum cannot be greater than 12.)

  2. 2

    6

    6

    6

    Returns: 1.0

    Given that at least one of the dice shows a 6 the sum of the 2 dice must be at least 7.

  3. 1

    9

    3

    3

    Returns: 1.0

  4. 2

    3

    2

    4

    Returns: 0.6

    Two 3-sided (!) dice with at least one 2 showing: 12 22 32 21 23 are the 5 possible equally likely results, and 3 of the 5 have a sum greater than or equal to 4.

  5. 50

    50

    50

    1

    Returns: 0.9999999999999967

  6. 50

    50

    1

    1234

    Returns: 0.6065038966315277

  7. 3

    1

    1

    2

    Returns: 1.0

  8. 3

    1

    1

    3

    Returns: 1.0

  9. 3

    2

    2

    6

    Returns: 0.14285714285714285

  10. 50

    2

    2

    76

    Returns: 0.44386241367039186

  11. 50

    2

    1

    75

    Returns: 0.5561375863296081

  12. 50

    30

    1

    1300

    Returns: 2.5399419266958173E-23

  13. 5

    30

    1

    75

    Returns: 0.27533413164043663

  14. 1

    4

    4

    3

    Returns: 1.0

  15. 20

    4

    4

    27

    Returns: 0.9999999720718009

  16. 9

    6

    5

    31

    Returns: 0.6268537748023865

  17. 31

    40

    20

    367

    Returns: 0.9999930562338223

  18. 14

    13

    11

    151

    Returns: 5.453029923318587E-5

  19. 29

    13

    10

    297

    Returns: 7.795014737059219E-7

  20. 34

    26

    22

    563

    Returns: 0.010441662002489594

  21. 19

    17

    7

    232

    Returns: 0.0013834917661672413

  22. 12

    38

    14

    388

    Returns: 5.775198675184631E-7

  23. 39

    10

    2

    362

    Returns: 7.316645457324389E-23

  24. 39

    5

    5

    108

    Returns: 0.8585970614298535

  25. 24

    37

    19

    231

    Returns: 0.9999975047685218

  26. 26

    41

    9

    830

    Returns: 8.861924833662333E-8

  27. 3

    48

    21

    40

    Returns: 0.9321908701433004

  28. 48

    26

    14

    99

    Returns: 0.9999999999999993

  29. 21

    42

    19

    862

    Returns: 0.0

  30. 49

    32

    10

    173

    Returns: 1.0000000000000002

  31. 34

    30

    7

    614

    Returns: 0.03345959839326994

  32. 46

    2

    1

    69

    Returns: 0.5585020439387954

  33. 22

    11

    1

    75

    Returns: 0.9999642798272311

  34. 37

    2

    1

    6

    Returns: 1.0

  35. 30

    29

    11

    835

    Returns: 1.082803357398144E-30

  36. 23

    9

    1

    122

    Returns: 0.27422716822202015

  37. 15

    49

    25

    353

    Returns: 0.6623121652697722

  38. 7

    49

    5

    149

    Returns: 0.5868050160689797

  39. 24

    8

    8

    7

    Returns: 1.0000000000000002

  40. 22

    34

    25

    486

    Returns: 0.017276761759106717

  41. 32

    44

    35

    877

    Returns: 0.018148482714944094

  42. 38

    42

    36

    1401

    Returns: 2.1820394590906484E-18

  43. 34

    46

    41

    174

    Returns: 0.9999999999999998

  44. 1

    8

    8

    3

    Returns: 1.0

  45. 48

    50

    27

    235

    Returns: 0.9999999999999989

  46. 14

    19

    11

    211

    Returns: 1.32940448169323E-4

  47. 12

    18

    11

    49

    Returns: 0.9999827581018343

  48. 50

    4

    4

    114

    Returns: 0.9270471837179275

  49. 9

    38

    7

    310

    Returns: 2.2975880608148006E-12

  50. 41

    32

    18

    1226

    Returns: 4.284894444082593E-30

  51. 44

    33

    4

    448

    Returns: 0.9999993000184015

  52. 12

    38

    7

    375

    Returns: 2.020161856917486E-6

  53. 26

    34

    2

    220

    Returns: 0.9999992301535131

  54. 12

    37

    21

    180

    Returns: 0.9196250744358586

  55. 49

    38

    38

    998

    Returns: 0.33174712168162546

  56. 50

    50

    48

    1666

    Returns: 7.534739841501312E-5

  57. 50

    50

    25

    200

    Returns: 0.9999999999999997

  58. 50

    50

    1

    1

    Returns: 0.9999999999999992

  59. 50

    50

    38

    1200

    Returns: 0.792839402396853

  60. 50

    50

    50

    1200

    Returns: 0.813885451334627

  61. 50

    50

    1

    1250

    Returns: 0.5443439491287221

  62. 50

    50

    35

    1250

    Returns: 0.6199599173066064

  63. 50

    50

    34

    1978

    Returns: 1.9798976937437787E-13

  64. 50

    50

    6

    100

    Returns: 0.9999999999999988

  65. 50

    50

    50

    2500

    Returns: 1.770755296785606E-85

  66. 50

    50

    30

    1000

    Returns: 0.9970818543000018

  67. 50

    50

    50

    2499

    Returns: 9.030852013606592E-84

  68. 50

    50

    32

    1349

    Returns: 0.2463888390005133

  69. 50

    50

    30

    1200

    Returns: 0.7788946791076431

  70. 50

    50

    21

    200

    Returns: 0.9999999999999992

  71. 50

    50

    23

    1250

    Returns: 0.59342105224914

  72. 49

    47

    23

    1230

    Returns: 0.2839462500117616

  73. 50

    50

    50

    2000

    Returns: 4.2082315493315665E-14

  74. 50

    50

    50

    1119

    Returns: 0.9555720210984059

  75. 50

    50

    30

    465

    Returns: 0.9999999999999996

  76. 50

    50

    25

    1500

    Returns: 0.01319355483009048

  77. 33

    16

    16

    474

    Returns: 2.1789896914338626E-16

  78. 50

    50

    25

    300

    Returns: 0.9999999999999997

  79. 50

    50

    17

    997

    Returns: 0.9966371988641942

  80. 50

    50

    35

    1300

    Returns: 0.4259162818274663

  81. 50

    50

    1

    1000

    Returns: 0.9954527270692969

  82. 50

    30

    20

    1500

    Returns: 0.0

  83. 50

    50

    48

    1666

    Returns: 7.534739841501312E-5

  84. 50

    50

    25

    200

    Returns: 0.9999999999999997

  85. 50

    50

    1

    1

    Returns: 0.9999999999999992

  86. 50

    50

    38

    1200

    Returns: 0.792839402396853

  87. 50

    50

    50

    1200

    Returns: 0.813885451334627

  88. 50

    50

    1

    1250

    Returns: 0.5443439491287221

  89. 50

    50

    35

    1250

    Returns: 0.6199599173066064

  90. 50

    50

    34

    1978

    Returns: 1.9798976937437787E-13

  91. 50

    50

    6

    100

    Returns: 0.9999999999999988

  92. 50

    50

    50

    2500

    Returns: 1.770755296785606E-85

  93. 50

    50

    30

    1000

    Returns: 0.9970818543000018

  94. 50

    50

    50

    2499

    Returns: 9.030852013606592E-84

  95. 50

    50

    32

    1349

    Returns: 0.2463888390005133

  96. 50

    50

    30

    1200

    Returns: 0.7788946791076431

  97. 50

    50

    21

    200

    Returns: 0.9999999999999992

  98. 50

    50

    23

    1250

    Returns: 0.59342105224914

  99. 49

    47

    23

    1230

    Returns: 0.2839462500117616

  100. 50

    50

    50

    2000

    Returns: 4.2082315493315665E-14

  101. 50

    50

    50

    1119

    Returns: 0.9555720210984059

  102. 50

    50

    30

    465

    Returns: 0.9999999999999996

  103. 50

    50

    25

    1500

    Returns: 0.01319355483009048

  104. 33

    16

    16

    474

    Returns: 2.1789896914338626E-16

  105. 50

    50

    25

    300

    Returns: 0.9999999999999997

  106. 50

    50

    17

    997

    Returns: 0.9966371988641942

  107. 50

    50

    35

    1300

    Returns: 0.4259162818274663

  108. 50

    50

    1

    1000

    Returns: 0.9954527270692969

  109. 50

    30

    20

    1500

    Returns: 0.0


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