\f3.24 Osteoporosis. The World Health Organization defines osteoporosis in young adults as a measured bone mineral density 2.5 or more standard deviations below the mean for young adults. Assume that bone mineral density follows a normal distribution in young adults. What percentage of young adults suffer from osteoporosis according to this criterion?3.38 Stenographer's typos. A very skilled court stenographer makes one typographical error (typo) per hour on average. (a) What are the mean and the standard deviation of the number of typos this stenographer makes in an hour? (b) Calculate the probability that this stenographer makes at most 3 typos in a given hour. (c) Calculate the probability that this stenographer makes at least 5 typos over 3 hours