GingerAle

avatar
UsernameGingerAle
Score1912
Membership
Stats
Questions 2
Answers 601

 #6
avatar+1912 
0
Sep 23, 2016
 #4
avatar+1912 
+5

Happy Birthday Miss Rosala!smiley

 

I thought this was your 16th birthday, too.

 

This is why I thought so:

 

http://web2.0calc.com/questions/todays-my-birthday#r6

 

Birthdays are funny things. When we are younger, we want to add a few to them, and when we are older, we want to subtract a few from them.

 

P.S. I like the photos of your Uncle. He is very handsome. I think it’s very cool we have the nice of India’s Prime Minster on this forum. smiley

Sep 23, 2016
 #6
avatar+1912 
+5

Here’s my logic.

 

This is a weighted average of probability.  The weights are proportional to the probability of each event.

The first event is the probability of either a black ball or a white ball.  Four of the five bálls are black and one is white. The black ball has a (4/5) 0.80 probability and the white ball has a (1/5) 0.20 probability of being drawn

 

IF a black ball (0.80 probability) is drawn, then bin “b” probabilities are in play.

The weights are calculated the same as above. There are four b***s – three are $1 bálls and one is a $7 ball. The probability of drawing a $1 ball is (3/4) 0.75 and the probability of drawing a $7 is (1/4) 0.25

0.75 * $1 = 0.75

0.25 * 7$ = 1.75

Total       =  2.50 average per event

$2.50* 0.80 (Black ball Probability) = $2.00

 

The logic for the white ball event is the same.

---------------------

Ugh!  CDD strikes again!!

I’m not posting it because I see from Sir Alan’s post that my numbers are wrong. I was using one $500-ball and eight $8-bálls. (I think I added 1 to the 8 instead of the five).

 

 I added Sir Alan’s solution to Naus’ Tortoise and Hair AI formula for blonds, so it now works for red-heads.laugh

-----------------------

Here's the fully repaired answer:

 

Black Ball probability 0.80

 

                                $1 Ball drawn probability 0.75    Expected Value = 0.80 * 0.75 * 1 =  $0.60

                                $7 Ball drawn probability 0.25    Expected Value = 0.80 *0.25 * 7 =   $1.40

                                                                                                                          Sum         $2.00

White Ball probability 0.20

 

                           $8 Ball drawn probability (5/6) 0.8333 Expected Value = 0.20 * 0.8333* 8 = $1.33 

                       $500 Ball drawn probability (1/6) 0.1667 Expected Value = 0.20 * 0.1667 * 500 = 16.67

                                                                                                                                    Sum         $18.00

18.00+2.00 = $20.00 Expected Value

Sep 18, 2016