In: Advanced Math
There are a total of 10 test stations. When a circuit board fails, the test station will automatically record the lifetime for the failed board and then immediately switch to a replacement board. The test was stopped at 1200 hours. At that time, 19 circuit boards had failed and there was an operating circuit board in every station. Assuming the boards have exponentially-distributed lifetimes, estimate the mean lifetime for this type of board.