Over time, the number of original basic words in a language tends to decrease as words become obsolete or are replaced with new words. In 1950, C. Feng and M. Swadesh established that of the original 210 basic ancient Chinese words from 950 A.D., 167 were still being used. The proportion of words that remain after t millennia is a random variable that is exponentially distributed with a = 0.229.

(a) Find the life expectancy and standard deviation of a Chinese word.
(b) Calculate the probability that a randomly chosen Chinese word will remain after 2000 years.