NCERT Class XI Mathematics - Linear Inequalities - Solutions
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Question : 21
Total: 65
Ravi obtained 70 and 75 marks in first two unit tests. Find the minimum marks he should get in the third test to have an average of at least 60 marks.
Solution:
Let Ravi gets x marks in third unit test.
∴ Average marks obtained by Ravi =
He has to obtain atleast 60 marks,
∴
Multiplying both sides by 3, 145 + x ≥ 60 × 3 = 180
Transposing 145 to R.H.S., we get x ≥ 180 – 145 = 35
∴ Ravi should get atleast 35 marks in the third unit test.
∴ Average marks obtained by Ravi =
He has to obtain atleast 60 marks,
∴
Multiplying both sides by 3, 145 + x ≥ 60 × 3 = 180
Transposing 145 to R.H.S., we get x ≥ 180 – 145 = 35
∴ Ravi should get atleast 35 marks in the third unit test.
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