Ravi obtained 70 and 75 marks in first two unit test. Find the minimum marks he should get in the third test to have an average of at least 60 marks.

Let us assume, x be the marks obtained by Ravi in his third unit test

According to question, the entire students should have an average of at least 60 marks

∴

= 145 + x ≥ 180

= x ≥ 180 - 145

= x ≥ 35

Hence, all the students must obtain 35 marks in order to have an average of at least 60 marks