when 3 dice are rolled find the probability of getting a sum of 13?

• 14. There are 2 groups named brown and red. They can n't marry in the same group. If the husband or wife dies then the person will revert to their own group. If a person is married then the husband will have to change his group to his wife's group. Children will own the mother's group. If man is red then his mother's brother belong to which group if he is married
  a. red
  b. brown
  c. red and brown
  d. none
• 8 years agoHelpfull: Yes(24) No(1)
• x+y+z=13 => x+y=13-z
  for z=1 x,y (6,6)
  z=2 (5,6)(6,5)
  z=3 (6,4)(4,6)(5,5)
  similarly z=6 have 6 pair
  so 1+2+3+4+5+6=21
  total=6x6x6=216
  ans=21/216=7/72
• 8 years agoHelpfull: Yes(19) No(0)
• Total Space6^3=216
  Possible Ways
  1 6 6 3i/2i =3+
  2 5 6 3i=6+
  3 4 6 3i=6 +
  3 5 5 3i/2i=3+
  4 4 5 3i/2i=3
  ===21 possible ways
  
  21/216 Is answer
  
• 8 years agoHelpfull: Yes(13) No(0)
• @piyali
  correction in the ans it would be brown as mother would be red and than her married brother would be in another group i.eof brown
• 8 years agoHelpfull: Yes(5) No(1)
• answer is 21/216
  as there are 6 dices rolling together 6^3=216 which is total probability
  now for the case getting sum =13
  we can fix one dice and roll othr two dice
  like taking 1st dice outcome as 1 so we need 12 as sum from othr two dice so the probable cases would be:
  1,6,6
  similarly taking 1st dice to be 2, we get:
  2,6,5
  2,5,6
  3,5,5
  3,4,6
  3,6,4
  4,4,5
  4,5,4
  4,6,3
  4,3,6
  5,5,3
  5,3,5
  5,6,2
  5,2,6
  5,4,4
  6,1,6
  6,2,5
  6,3,4
  6,4,3
  6,5,2
  6,6,1
  so total cases are 21
  thus ans is 21/216
  
• 8 years agoHelpfull: Yes(5) No(0)
• FOR 3 DICE
  SUM=13
  PROBABILITY=21/216
  
• 8 years agoHelpfull: Yes(1) No(1)
• 7/72
  total sample spaces=6^3=216
  probability=6+5+4+3+2+1/216=7/72
• 8 years agoHelpfull: Yes(0) No(3)
• Answer is 21.
  
  Use formula
  suppose k is the sum of three dices we want
  then for 3
• 8 years agoHelpfull: Yes(0) No(2)
• Answer is 21/216 or 7/72
  Use formula
  suppose k is the sum of three dices we want
  then for 3
• 8 years agoHelpfull: Yes(0) No(1)
• 1/36
  n(s)=216
  n(E)=6
  p(E)=6/216=1/36
• 7 years agoHelpfull: Yes(0) No(1)