- Figure 7.16 - P( 3 . Find the probability that one review will take Yoonie from 3.5 to 4.25 hours. Sketch the graph, labeling and scaling the horizontal axis. Shade the region corresponding to the probability. - Figure 7.16 0 Pl 290)? 26 . True or False: only the sums of normal distributions are also normal distributions. 2'! . In order for the sums of a distribution to approach a normal distribution, what must be true? 28 . What three things must you know about a distribution to find the probability of sums? 29 . An unknown distribution has a mean of 25 and a standard deviation of six. Let X = one object from this distribution. What is the sample size if the standard deviation of IX is 42? 30 . An unknown distribution has a mean of 19 and a standard deviation of 20. Let X = the object of interest. What is the sample size if the mean of EX is 15,200? Use the following information to answer the next three exercises. A market researcher analyzes how many electronics devices customers buy in a single purchase. The distribution has a mean of three with a standard deviation of 0.7. She samples 400 customers. 31 . What is the z-score for Ex 2 840? 32 . What is the z-score for Ex 2 1,186? 33. What is P()_'x 9,000)? 7.3 Using the Central Limit Theorem Use the following information to answer the next ten exercises: A manufacturer produces 25-pound lifting weights. The lowest actual weight is 24 pounds, and the highest is 26 pounds. Each weight is equally likely so the distribution of weights is uniform. A sample of 100 weights is taken. 37 . - What is the distribution for the weights of one 25-pound lifting weight? What is the mean and standard deviation? What is the distribution for the mean weight of 100 25- pound lifting weights? - Find the probability that the mean actual weight for the 100 weights is less than 24.9. 38 . Find the probability that the mean actual weight for the 100 weights is greater than 25.2. 39 . Find the 90m percentile for the mean weight for the 100 weights. 4O - What is the distribution for the sum of the weights of 100 25-pound lifting weights? Find P(Zx 420). 51 . Find the 90m percentile for the sums. 52 . Find the 15th percentile for the sums. 53. Find the first quartile for the sums. 54. Find the third quartile for the sums. 55 . Find the 80th percentile for the sums