Over time, the number of original basic words in a language tends to decrease as words become obsolete or are replaced with new words. for a certain language proportion of words that remain after t millennia is a random variable that is exponentially distributed with a = 0.247. complete parts (a) and (b)
a. find the life expectancy and standard deviation of a word from this language.
what is the life expectancy?
4.05 millennia
what is the standard deviation?
4.05 millennia
b. what is the probability that a randomly chosen word from this language will remain after 2000 years?
(round to four decimal places as needed)

Johnson company uses the allowance method to account for uncollectible accounts receivable. bad debt expense is established as a percentage of credit sales. for 2018, net credit sales totaled $6,400,000, and the estimated bad debt percentage is 1.40%. the allowance for uncollectible accounts had a credit balance of $61,000 at the beginning of 2018 and $49,500, after adjusting entries, at the end of 2018.required: 1. what is bad debt expense for 2018 as a percent of net credit sales? 2. assume johnson makes no other adjustment of bad debt expense during 2018. determine the amount of accounts receivable written off during 2018.3. if the company uses the direct write-off method, what would bad debt expense be for 2018?