To receive Grade ‘A’ in a course, one must obtain an average of 90 marks or more in five examinations (each of 100 marks). If Sunita’s marks in first four examinations are 87, 92, 94 and 95, find minimum marks that Sunita must obtain in fifth examination to get grade ‘A’ in the course

Solution:

Let x be the marks obtained by Sunita in the fifth examination

In order to receive grade ‘A’ in the course, she must obtain an average of 90 marks or more in five examinations

Therefore,

(87 + 92 + 94 + 95 + x)/5 ≥ 90

⇒ (368 + x)/5 ≥ 90

⇒ 368 + x ≥ 450

⇒ x ≥ 450 - 368

⇒ x ≥ 82

Thus, Sunita must obtain a minimum of 82 marks in the fifth examination

NCERT Solutions Class 11 Maths Chapter 6 Exercise 6.1 Question 22

To receive Grade ‘A’ in a course, one must obtain an average of 90 marks or more in five examinations (each of 100 marks). If Sunita’s marks in first four examinations are 87, 92, 94 and 95, find minimum marks that Sunita must obtain in fifth examination to get grade ‘A’ in the course

Summary:

A linear inequation (87 + 92 + 94 + 95 + x)/5 ≥ 90 can be formed. We have found that Sunita must obtain a minimum of 82 marks in the fifth examination