Question:
The marks scored by Rohit in two tests were 65 and 70. Find the minimum marks he should score in the third test to have an average of at least 65 marks.
Solution:
Let x be the minimum marks he scores in the third test.
Then, $\frac{65+70+x}{3} \geq 65$
$\Rightarrow \frac{135+x}{3} \geq 65$
$\Rightarrow 135+x \geq 195 \quad$ (Multiplying both the sides by 3$)$
$\Rightarrow x \geq 195-135$
$\Rightarrow x \geq 60$
Hence, the minimum marks Rohit should score in the third test should be 60 .