Ask Questions, Get Answers

Want to ask us a question? Click here
Browse Questions
Home  >>  CBSE XI  >>  Math  >>  Linear Inequalities
0 votes

To receive Grade $'A'$ in a course, one must obtain an average of $90$ marks or more in fine. examination (each of $100$ marks ) . If sunita's mark in first four examinations are $87,92,94 $ and $95$ find the minimum marks that sunita must obtains in the fifth examination to get grade $'A'$ in the corse

$\begin{array}{1 1} (A)\;78 \\(B)\;35 \\(C)\;56 \\(D)\;82 \end{array} $

Can you answer this question?

1 Answer

0 votes
  • Same Quantity can be added (a subtracted ) to (from ) both sides of the inequality with out changing the sign of the in equality.
  • Same positive quantities can be multiplied or divided to both side of the in equality with out changing the sign of the inequality.
  • If same negative quantity is multiplied or divided to both sides of the inequality is reversed i.e $ '>'$ sign changes to $'<' $ and $'<'$ changes $'>'$ .
Let x be the marks sunita obtained in the fifth examination.
Total marks obtained in all five examination is
$87 +92+94 +95+x $
To get grade A the average must be greater than or equal 90.
Thus $ \large\frac{87 +92+94 +95+x}{5} $$ \geq 90$
$=> \large\frac{368 +x}{5} $$ \geq 90$
Multiplying both sides by positive number 5.
$=> 368 +x \geq 450$
Subtracting 368 from both sides,
$=> x \leq 450 -368$
$=> x \geq 82$
Step 2:
Sunitha must obtain atleast 82 marks to get grade A.
Hence D is the correct answer.
answered Jul 28, 2014 by meena.p

Related questions

Ask Question
student study plans
JEE MAIN, CBSE, AIPMT Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App