Question

Example 48
A slip of paper is given to person A who marks it with either a plus or a
minus sign. The probability of his writting a plus sign is A passes the slip to
B, who may either leave it alone or change the sign before passing it to C. Next
C passes the slip to D after perhaps changing the sign the referee sees a plus
sign on the slip. It is known that B, C and D each change the sign with probability
2
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What is the probability that A originally write a plus?​

Answer 1

Answer:1/16

Step-by-step explanation:

1/2×1/2×1/2×1/2=1/16

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