Random Math Thread : Puzzles , Jokes , Problems, Funny Anecdotes, Random Thoughts

[Big Slick]

What are the odds in Texas holdem poker to make a straight flush using both of your hole cards?

[CincySportsFan]

And one more probability question... I've had people argue up and down about this one.

 

John has three children. If you are told that at least one of the children is a boy, what's the probability that John has three sons?

 

BBB

BBG

BGG

 

Keep going... There are some other sample points(consider order).

 

If we didn't have any pre-knowledge of at least one boy and just knew he had three kids, the sample space would be:

 

S = { BBB, BBG , BGB, GBB , GBG, BGG, GGB, and GGG}

 

P( all boys) would be 1/8.

 

However, since we know he has at least one boy, the GGG sample point is eliminated from the sample space. Hence, the sample space for this conditional probably would include only seven sample points.

P(three boys) = P(BBB) = 1/7

 

Defies logic.

 

He can either have

 

3 boys

2 boys and 1 girl

1 boy and 2 girls

 

I think Clyde is on the right track, with the small exception that all three of his possibilities are not equal. I also think your answer is incorrect as well. Here's the way I looked at it...knowing that at least 1 of the kids is a boy.

 

If the boy (that you are certain of) is the oldest, you could get the following combinations: BGG, BGB, BBG, BBB

 

If the boy happens to be the middle child, you could get the following combinations: GBG, GBB, BBG, BBB

 

And likewise, if the boy happens to be the youngest of the three, you could get: GGB, GBB, BGB, BBB

 

Therefore you have 12 possibilities, of which 3 are all boys. So the percentages (using Clyde's possibilities) are:

 

3 Boys = 25%

2 Boys + 1 Girl = 50%

1 Boy + 2 Girls = 25%

 

The option of having 3 girls is never even considered to be part of the sample space, because you are guaranteed that one of the children is a boy.

[Big Slick]

What are the odds in Texas holdem poker to make a straight flush using both of your hole cards?

Anybody?

[WhoozYoDaddy]

I put instant coffee in the microwave oven and I went back in time.

-Steven Wright-

[Clyde]

How far out can you divide any number by 9 in your head? Easier than you think.

 

Ex:

 

87 / 9 = 9.6667

74/9 = 8.2222

17/9 = 1.8889

 

You can do it in your head if you can do basic division.

 

9 is an interesting number (sort of like 11) when it comes to division.

 

The way to do it in your head is to take how many times 9 goes into the number. So 87 - 9 * 9 = 81. So the number before the decimal is 9. Easy. The part that will wow your dinner guests is the numbers behind the decimal. Every number after the decimal is the same.

 

It in our case using 87 we just take 87 - 81 (9*9) = 6. 9.66666666666666.

74 = 74 - 72 (9*8) = 2 so we have 8.222222222.

 

Impress your neighbors and your former math teacher.

[Science Friction]

I think Clyde is on the right track, with the small exception that all three of his possibilities are not equal. I also think your answer is incorrect as well. Here's the way I looked at it...knowing that at least 1 of the kids is a boy.

 

If the boy (that you are certain of) is the oldest, you could get the following combinations: BGG, BGB, BBG, BBB

 

If the boy happens to be the middle child, you could get the following combinations: GBG, GBB, BBG, BBB

 

And likewise, if the boy happens to be the youngest of the three, you could get: GGB, GBB, BGB, BBB

 

Therefore you have 12 possibilities, of which 3 are all boys. So the percentages (using Clyde's possibilities) are:

 

3 Boys = 25%

2 Boys + 1 Girl = 50%

1 Boy + 2 Girls = 25%

 

The option of having 3 girls is never even considered to be part of the sample space, because you are guaranteed that one of the children is a boy.

 

You have five too many sample pts. BBB is listed three times, BBG(twice), BGB(twice), and GBB(twice). These four should be listed just one time each, giving you seven sample points. The answer is 1/7 . Also, if there were twelve sample points(all equally likely @ 1/2 X 1/2 X 1/2 = 1/8) , then you would have 12 X 1/8 = 12//8 . Add the GGG and you get 13/8, which is impossible since the probability of a sample space must = 1.

 

P( all three boys GIVEN at least one boy) = 1/7

[Science Friction]

How far out can you divide any number by 9 in your head? Easier than you think.

 

Ex:

 

87 / 9 = 9.6667

74/9 = 8.2222

17/9 = 1.8889

 

You can do it in your head if you can do basic division.

 

9 is an interesting number (sort of like 11) when it comes to division.

 

The way to do it in your head is to take how many times 9 goes into the number. So 87 - 9 * 9 = 81. So the number before the decimal is 9. Easy. The part that will wow your dinner guests is the numbers behind the decimal. Every number after the decimal is the same.

 

It in our case using 87 we just take 87 - 81 (9*9) = 6. 9.66666666666666.

74 = 74 - 72 (9*8) = 2 so we have 8.222222222.

 

Impress your neighbors and your former math teacher.

 

No guarantee they will be impressed.I showed this to some smart alleck once and got kicked in the balls for my efforts.

 

So much for trying to spread my love for math.

[hoops5]

A couple days late....

 

December 20: On this day in history, the flag of the United States was officially raised in New Orleans on this date in 1803, completing the transfer of the Louisiana Territories from France to the United States. The size of the United States was approximately doubled when it purchased 828,000 square miles of land for $15 million in the Louisiana Purchase. That land now makes up 23% of the territory of the U.S.

 

What is the approximate area of the United States today?

[Clyde]

How far out can you divide any number by 9 in your head? Easier than you think.

 

Ex:

 

87 / 9 = 9.6667

74/9 = 8.2222

17/9 = 1.8889

 

You can do it in your head if you can do basic division.

 

9 is an interesting number (sort of like 11) when it comes to division.

 

 

So if you're looking for that one thing that may get you "in" with that special someone who has thus far resisted your game try this "11" trick on them.

 

29/11 = 2.6363

35/11=3.1818

49/11=4.4545

 

See a pattern?

 

Without doing any hard mental math.

 

Find your whole number. 29/11 whole number is 2.

 

Remainder is 7.

Remainder less 1 is 6 so there's your first number to the right of the decimal.

The next number is always the number it takes to get from the first spot to the right of the decimal up to 9.

 

So 6 is the first number. To get to 9 you need 3 thus you get 2.63. It then repeats. 2.63636363636363.

 

You're in. Buy the engagement ring. Guaranteed winner.

 

Mental math is easy.

[WhoozYoDaddy]