Suppose a research paper states that the distribution of the daily sea-ice advance/retreat from each sensor is similar and is approximately double exponential. The proposed double exponential distribution has density function

f(x) = 0.5e^|x|

for < x < . The standard deviation is given as 39.9 km. (Round your answers to four decimal places.)

(a) What is the value of the parameter ? = ________ (b) What is the probability that the extent of daily sea-ice change is within 1 standard deviation of the mean value?