To understand the problem of terver?

Question

Probability theory

Task:
According to the test data of a large batch of devices, it was found that 0.1 percent of devices fail in 2000 hours. Find the probability of failure-free operation of the device for 40,000 hours.

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Answer 1

After 2000 hours (1-1/1000) devices will survive, for the next 2000 - (1-1/1000) of the remaining ones, etc. After 40000 hours, (1-1/1000)^(40000/2000) ~ 98% will remain. Actually, this is the answer.

Answer 2

Start here:
Wentzel E.S. Probability theory