plz help..probablity....tomorrow paper...

probablity misc exercise q11.....

in a game a man wins a rupee for a six and loses a rupee for any other number when a fair die is thrown.a man decides to throw a die thrice but to quit as soon as he gets a six.Find expected value of amount he wins or loses...............

i tried it with PDF....but my answer is not matching.......
plz help.....

15 Answers

1
KR ·

x be the random variable of no of sixes in 3 throws of a dice

so x=0,1,2,3..........

62
Lokesh Verma ·

no need to get into pdf.

winning 1 rupee is winning on the first move
winning 0 rupee is winning on 2nd move
losing 1 rupee is winning on 3rd move
losing 3 rupees ...
hence

1.1/6 +0 -1.5/6.5/6.1/6 - 3. 5/6.5/6.5/6 (thanks akand and chinmay)

1
Akand ·

but bhaiyya..........................so the expected value of the amount he wins is 11/216????????????? hws that? isnt it odd?....a fraction of money??

1
Akand ·

and wat about if he loses a\on all the three turns?????
so shudnt we add -3(5/6)3

1
chinmay ·

yeah!! Why not losing 3 rupee by losing all the three tries??

62
Lokesh Verma ·

yup corrected

1
Akand ·

k.......thanx bhaiyya.............

9
Celestine preetham ·

yes eureka

this was a wrong ncert q

i rememember getting 13/ something as ans ( long time ago )

but ans dint match

however its solved correctly in rd sharma see if ur ans matches in that

24
eureka123 ·

sir yehi to pdf se bhi aa raha hai............but can it be negative??????????

62
Lokesh Verma ·

yes it can be

it means it is expected that he can lose money..

24
eureka123 ·

ok.......thanx sir for help....

i got the same ans from pdf .......but ncert confused me[2][2][2]

1
ankit mahapatra ·

But if its not given what will he do if he doesn't get a six in either of the three throws. then why should we consider it.

9
Celestine preetham ·

small dbt wats pdf ???

24
eureka123 ·

@ celestine.......pdf=probablity distribution function

9
Celestine preetham ·

k thnks

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