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Math
Middle School Math

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 2 Professor Floop inspected the glassware in the storeroom once a month. There were 1500 pieces of glassware at the beginning of the semester. The first month he found five items that were cracked. The second month he found two. The third month he found five. After his fourth and final inspection of the semester he calculated that on average there were 4.5 pieces damaged per month. How many damaged pieces must he have found during the last inspection?
 3 James performed a reaction that resulted in the precipitation of 5 g of silver chloride in a beaker. Rebecca and Shelby performed the same reaction and got 5.8 g and 6.5 g, respectively. The instructor told them that the most silver chloride he had seen produced in the reaction was 6.4 g. Find the average of the three students' results and compare it (as a percent) to the maximum amount seen by the teacher.
 4 Anna and Nicholas work in the purchasing department for SuperChem. The production manager e-mailed the purchasing department requesting a fresh supply of benzene. Nicholas immediately ordered eighteen 500-ml bottles. After lunch, Anna also saw the message and ordered eight 1.4 liter bottles. Unknown to either one of them, another buyer had predicted that they would need more benzene and ordered three 2-gallon containers. What was the average amount of benzene that the three buyers ordered? _____ liters.
 5 Danielle measured the pH in a flask of acidic solution several times. She was slowly adding more acid trying to reach a stable pH of 5.5. Every time she would add a few drops of acid, the pH would drop. A few minutes after she added drops of acid the pH would start to rise. So she kept this up and finally read the pH six times over a period of five minutes without adding more acid. The six pH measurements were 5.4, 5.35, 5.36, 5.43, 5.39, and 5.35. What is the range of her measurements?
 6 Mr. Bloop was separating three organic liquids by distillation. He put 100 ml of a mixture into a distillation flask and set about heating it up. He began flowing water through the condenser and watched as the temperature rose. The temperature stopped rising and was stable at 89C for 5 minutes 15 seconds and the mixture boiled. Then it slowly rose to 96C and stabilized for 12 minutes and 37 seconds where it boiled for awhile and then it rose again to 99C and stayed there for 8 minutes. He stopped the process. What was the average time (in minutes and seconds) that the liquid was stable at a boiling point?