Riddles, brain puzzles and mathematical problems

[BAndrew]

No. All the question asks is whether a current can flow across the circuit. That said, the five switches drawn in the circuit can be either closed or open. They are only shown as open to let you know that they are switches.

What do you mean by "across"?

It can either go the upper way (that with the three switches) or the lower way (with the two switches). Or not?

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I think the five switches seen in the picture each simply have a probability of 1/3 to be open and 2/3 to be closed everytime you start the current. Closed switch means current can travel over it.

Well thank you that should be my mistake! So it will (probably) be 2/3 * 2/3 *2/3 + 2/3 * 2/3 - (2/3)^5 =
72/243 + 108/243 - 32/243 = 148/243 =~ 0,609 =~ 60,9%