# Model 1. A student taking a class will receive a grade based upon the following percentages:…

Model 1. A student taking a class will receive a grade based upon the following percentages: • test average 50% • homework average 20% • final exam grade 30% Her grades were: • 5 tests grades of 75, 65, 71, 52, and 87. Average = 70 • 8 homework grades of 90, 80, 10, 75, 92, 105, 90, and 100. Average = 80.3 • final examination grade of 79. Her final grade for the course was 75. 1. Using the information given in Model 1, answer the following questions. a. How was the average test grade and average homework grade calculated? b. Are the individual test grades weighted equally when determining the average? c. How much will the test average contribute to the final grade total? d. How was the final grade that this person received calculated? e. Are the test average, homework average and exam grade weighted equally (worth the same amount) when calculating the final grade? Model 2. Most elements exist in several different forms called isotopes. The isotopes of an element always have the same number of protons, but the number of neutrons and therefore the mass number and subsequently the actual mass of the atom is different. Silicon exists as a mixture of three isotopes. The percent abundance represents the number of each isotope that exists. The atomic mass given on the Periodic Table for silicon is 28.0855 u. This mass is based on the following data. Isotope Mass (u) Abundance fraction weighted mass 28Si 27.976 9265 92.23 % 0.9223 25.80 29Si 28.976 4947 4.67 % 0.0467 1.35 305i 29.973 7702 3.10 % 0.0310 0.93 Normal average: 28.9757305 100.00% 1.0000 weighted average: 28.08 2. Given the information in Model 2