Lab #6 Name STAT 2450 Chapter 6: Normal Distribution 1. A student received a 40 on a math quiz that had a mean of 55 and standard deviation of 8. She received a 50 on a biology quiz that had a mean of 60 and standard deviation of 5. On which quiz did she do better relative to the rest of the class? 2. The weights of full-grown Old English Sheepdogs are normally distributed with a mean of 66 pounds and a standard deviation of 3.4 pounds. a) What is the probability that a new puppy of this breed will eventually weigh more than 72 pounds? b) Is this considered unusual? Support your answer numerically. e) What is the weight of a Jll-grown Old English Sheepdog in the 40th percentile? 3. Based on data collected from its production processes, Crosstiles, Inc. determines that the breaking strength of its most popular porcelain tile is normally distributed with a mean of 370 paunds per square inch and a standard deviation of 9.? pounds per square inch. a. AbOut what percent of its popular porcelain tile will have breaking strengths greater than 390 pounds per square inch? b. Describe the breaking strength of the strongest 10% of its popular porcelain tile. c. About what percent of Crosstile's popular porcelain tile will have breaking points between 325 and 385 pounds per square inch? 4. A company's manufacturing process uses 500 gallons of water at a time. A \"scrubbing\" machine then removes most of the chemical pollutant before pumping the water into a nearby lake. To meet federal regulations the treated water must not contain more than 80 parts per million (ppm) of the chemical. Because a ne is charged if regulations are not met, the company sets the machine to attain an average of 74 ppm in the treated water. The machine's output is normally distributed with a standard deviation of 2.9 ppm. What percent of the batches of water discharged exceed the 80 ppm standard