Questions & Answers

Question

Answers

A. $ a=b $

B. $ a>b $

C. $ b>a $

D. All of the above

Answer

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We have given that $ \left( 81\div 9 \right)\div 3=a $ and $ 81\div \left( 9\div 3 \right)=b $ .

We have to find that from given options, which is correct.

To compare the values of $ a $ and $ b $ , first we have to solve the given equations.

Let us consider equation $ \left( 81\div 9 \right)\div 3=a $

We will use the BODMAS rule to solve the given equations, according to the BODMAS rule first we have to solve the brackets.

So, we solve $ \left( 81\div 9 \right) $ , we get

$ \left( 81\div 9 \right)=9 $

Now, we have

$ \begin{align}

& 9\div 3=a \\

& a=3 \\

\end{align} $

Now, let us consider equation $ 81\div \left( 9\div 3 \right)=b $

First we solve $ \left( 9\div 3 \right) $ , we get

$ \left( 9\div 3 \right)=3 $

Now, we have

$ \begin{align}

& 81\div 3=b \\

& b=27 \\

\end{align} $

So, we get the values $ a=3 $ and $ b=27 $ , when we compare both, we get

$ \begin{align}

& 27>3 \\

& b>a \\

\end{align} $

For example- the given equations are $ \left( 81\div 9 \right)\div 3=a $ and

When we solve the given equations without using BODMAS rule, we get

$ \begin{align}

& \left( 81\div 9 \right)\div 3=a \\

& 9\div 3=a \\

& a=3 \\

\end{align} $

$ \begin{align}

& 81\div \left( 9\div 3 \right)=b \\

& 9\div 3=b \\

& b=3 \\

\end{align} $

We will get $ a=b $ and we choose option A as the correct answer but it is incorrect. So, be careful while solving such types of questions.