A guy has two wires of varying thickness, which each burns in 60 minutes. He actually wants to measure 45 mins. How can he measure 45 mins using only these two wires. (he can’t cut the one wire in half because the wires are non-homogeneous and he can’t be sure how long it will burn)

See Solution : Wires on fireHe will burn the first wire at both the ends and the second wire at one end. After half an hour, the first one burns completely and at this point of time, he will burn the other end of the second wire so now it will take 15 mins more to completely burn.. so total time is 30+15 i.e. 45mins.

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A-Life Software says

Wire 1 = W1, Wire 2 = W2

A1 —————- B1, A2 ————— B2 – A1 and B1 are two edges of W1, A2 and B2 are two edges of W2

Light up A1, A2 and B2 simultaneously.

When W2 is completely burned, it will be 30 minutes since you lit them up. Also, at this time W1 is half consumed.

Light up B1

When W1 is completely burned, it will be 15 minutes since you lit up W1.

And total time consumed = 30 + 15 = 45 mins