15.(A )For a standard normal distribution, the probability of obtaining a z value between ‐1.9 to 1.7 is:A) 0.9267B)0.4267C)1.4267D)0.500016.(D )The probability density function for a uniform distribution ranging between 2 and 6is:A) 0.4 B) 2 C) 6 D) 0.2517.(A )In its standardized form, the normal distribution:A) has a mean of 0 and a standard deviation of 1 B) has a mean of 1 and avariance of 0 C) has an area equal to 0.5 D) cannot be used to approximatediscrete probability distributions.18.(A)The value of the cumulative standardized normal distribution at Z is 0.8888. Thevalue of Z is:A) 1.22 B) 1.88 C) 2.44 D) 2.55.19.(B )The life expectancy of a particular brand of tire(某一特定品牌輪胎的使用壽命)isnormally distributed with a mean of 40,000 and a standard deviation of 5,000 miles.What percentage of tires will have a life of 34,000 to 46,000 miles?A) 38.49% B) 76.98% C) 50% D) 88.49%