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 Coin tossing (Posted on 2004-06-11)
I threw a coin n times, and never got three tails in a row. I calculated the odds of this event, and found out they were just about even; 50%-50%. How many times did I throw the coin?

A second question: what were the chances of having not gotten three heads in a row either?

 See The Solution Submitted by Federico Kereki Rating: 3.6667 (6 votes)

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 re: Exhaustion--1st and 2nd questions--the program | Comment 15 of 25 |
(In reply to Exhaustion--1st and 2nd questions by Charlie)

The program which produced the exhaustive list of H-T sequences and counted results is:

DECLARE SUB toss ()
OPEN "ctoss.txt" FOR OUTPUT AS #2
DIM SHARED s\$, Tctr, Hctr, Bctr, Nctr
toss
PRINT #2, : PRINT #2, "TTT"; Tctr; "; HHH"; Hctr; "; both"; Bctr; "; neither"; Nctr
CLOSE
END

SUB toss
IF LEN(s\$) = 10 THEN
PRINT #2, s\$; " ";
ix1 = INSTR(s\$, "TTT")
ix2 = INSTR(s\$, "HHH")
IF ix1 THEN PRINT #2, "TTT "; : Tctr = Tctr + 1
IF ix2 THEN PRINT #2, "HHH "; : Hctr = Hctr + 1
IF ix1 > 0 AND ix2 > 0 THEN Bctr = Bctr + 1
IF ix1 = 0 AND ix2 = 0 THEN Nctr = Nctr + 1
PRINT #2,
ELSE
s\$ = s\$ + "H"
toss
s\$ = LEFT\$(s\$, LEN(s\$) - 1) + "T"
toss
s\$ = LEFT\$(s\$, LEN(s\$) - 1)
END IF
END SUB

 Posted by Charlie on 2004-06-13 11:53:37

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