Question

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.

Answer 1

Let the marks obtained by Sunits in fifth examination be x.

Then average of five examinations

$=\frac{87+92+94+95+x}{5}$

Now $\frac{87+92+94+95+x}{5}\ge 90$

$\Rightarrow \frac{368+x}{5}\ge 90$

Multiplying both sides by 5, we have

$368+x\ge 450$

$\Rightarrow x\ge 450-368\Rightarrow x\ge 82$

Thus the minimum marks needed to be obtained by Sunita =82.