Exercise 7.7.10 The attention span of a two year-old is exponentially distributed with a mean of about 8 minutes. Suppose we randomly survey 60 two year-olds. a. In words, X = b. X~ c. In words, X = d. X~ e. Before doing any calculations, which do you think will be higher? Explain why. i. the probability that an individual attention span is less than 10 minutes; or ii. the probability that the average attention span for the 60 children is less than 10 minutes? Why? f. Calculate the probabilities in part (e). g. Explain why the distribution for X is not exponential.