Let x marks be scored by Tanvy in her last paper.
It is given that Tanvy scored 89, 93, 95 and 91 marks in first 4 papers.
To receive grade A, she must obtain an average of 90 marks or more.
Therefore,
\(\frac{89 + 93 + 85 + 91 + x}{5} \ge 90\)
Multiplying both the sides by 5 in the above equation
\(\big(\frac{89 + 93 + 95 + 91 + x}{5} \big) (5)\) \(\ge\) 90 (5)
368 + x ≥ 450
Subtracting 368 from both the sides in the above equation
368 + x – 368 ≥ 450 – 368
x ≥ 82
Therefore,
Tanvy should score minimum of 82 marks in her last paper to get grade A in the course.
