The time before failure of each platinum resistance thermometer used in a particular location is recorded. The times before failure in days for 10 successive thermometers are recorded as: 405 376 433...

The time before failure of each platinum resistance thermometer used in a particular

location is recorded. The times before failure in days for 10 successive thermometers are recorded as: 405 376 433 425 388 402 445 412 397 366.

Calculate the mean time to failure.