Calculating Weighted Average: In a History course, a student's grade is composed of papers (40%), tests (40%) and a final exam (20%). The student has earned a 90 value on all papers and 80 value on all tests. What is the minimum score the student needs to earn on the final exam to achieve an overall grade of a B+ (87.0)?

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Answers

  • Brainly User
2016-01-04T00:22:20+08:00
Papers = 90 (0.40)
Tests = 80 (0.40)
Final exam minimum score required = x (0.20)  
Average = 87
For the minimum score, linear inequality is involved in the problem. Use symbol ≥ .

Weighted Average Equation:

[(90)(0.40)]  + [(80)(0.40)] + [(0.20) (x)] ≥  87

36 + 32 +  0.20x ≥ 87

68 + 0.20x ≥ 87

0.20x ≥ 87 - 68

0.20x ≥ 19

0.20x ÷ 0.20   ≥  19 ÷ 0.20

x ≥ 95          
Solution = {x/x ≥ 95}  ;  interval = [95, ⁺∞)


ANSWER: The student must earn a minimum value, or score of at least, 95 in the final exam to get a B⁺ equivalent to 87.

Check:

36 + 32 + (0.20)(95) ≥ 87
68 + 19 ≥ 87
87 ≥ 87
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