help with the following:

Calculating a weighted average An instructor calculates course grades using a weighted average and the following scale: 15% homework, 15% projects, 10% group work, and 60% exams. (a) Currently, a particular student has the following homework scores: 95 90 95 89 96 97 96 87 88 98 95 94 The mean of these scores is 93.3 (b) Their project scores are as follows. 83 60 96 87 82 87 96 The mean of these scores is 84.43 (c) Their exam scores are as follows. 95 85 71 78 89 The mean of these scores is 83.6 (d) Their group grade is 95%; use the grade weights and the means above, and this information to calculate the students course grade. Hint: A weighted average is calculated by multiplying each category weight by each category grade. So weighted average = 0.15*(homework percent) + 0.15*(project percent) + 0.10*(95) + 0.60*(Exam percent). The weighted average is At the beginning of final's week before the nal exam, all course grades are in, and the student's course (weighted) average is the number calculated above. The nal exam is worth 20% of the grade (one-third of the 60% originally listed). (e) What grade does the student need on the final exam to keep a B? Hint: Since the nal exam grade is unknown, call it "x". Since 80% of the grade has already been determined, the course grade will be figured by computing: 0.8(86.32) + 0.2*x. If we want this to equal 80 (or more), we solve the equation 0.8(86.32) + 0.2*x = 80 for x. A nal exam score of What grade does the student need on the final exam to earn an A? Hint: You'll solve the equation above with 90 on the right instead of 80. A nal exam score of