Backdoor Probabilities

Question 1

Probability of backdoor straight

Answer 1

2 gapper: 1.48%

• (4/47 + 4/46)
• ex. 2-3-6, need 4 & 5

1 gapper: 2.96%

• (4/47 + 4/46)*2
• ex. 2-3-5, need 4 & (6 or A)

No gaps: 4.44%

• (4/47 + 4/46)*3
• ex. 3-4-5, need A & 2 or 2 & 6 or 6 & 7

Question 2

Probability of back door flush

Answer 2

4. 16%

- (10/47 + 9/47)

Question 3

Probability of backdoor 2 pair or trips with any two unpaired cards

Answer 3

1.4%