Question

Which pair of operations will make the equation below true when inserted into the blank spaces in the order shown? $2\dfrac{3}{{10}}\_\_\_1.5\_\_\_2 = 1.8$
(A) $ - $ and $ + $
(B) $ \times $ and $ + $
(C) $ + $ and $ - $
(D) $ \times $ and $ - $

Answer 1

Hint: The best approach for such type of questions would be verifying every option and trying to eliminate wrong options. Or we can try to compare the left hand side with the right hand side and try to guess the arithmetic operator using trial and error method.

Complete answer:
The given equation is $2\dfrac{3}{{10}}\_\_\_1.5\_\_\_2 = 1.8$
Now convert $2\dfrac{3}{{10}}$ into decimal form.
$\dfrac{{(2 \times 10) + 3}}{{10}} = \dfrac{{23}}{{10}} = 2.3$
Let’s start verifying one option after the other.
A. $ - $ and $ + $
After substituting the operators in the blanks, the equation becomes:
$2.3 - 1.5 + 2 = 2.3 + 0.5 = 2.8$
Since 2.8 is not equal to 1.8, this is not the right answer.

B. $ \times $ and $ + $
After substituting the operators in the blanks, the equation becomes:
$2.3 \times 1.5 + 2$
Using the BODMAS rule, we get:
$(2.3 \times 1.5) + 2 = 3.45 + 2 = 5.45$
Since, 5.45 is not equal to 1.8, this is not the right answer.

C. $ + $ and $ - $
After substituting the operators in the blanks, the equation becomes:
$2.3 + 1.5 - 2 = 2.3 - 0.5 = 1.8$
This is the right answer.

D. $ \times $ and $ - $
After substituting the operators in the blanks, the equation becomes:
$2.3 \times 1.5 - 2$
Using the BODMAS rule, we get:
$(2.3 \times 1.5) - 2 = 3.45 - 2 = 1.45$
Since 1.45 is not equal to 1.8, this is not the right answer.

Therefore, the correct option is C

Note: Here in this question, one should be familiar with BODMAS rule which is brackets of division multiplication addition subtraction, it tells us the priority order of different arithmetic operators which we used in options B and D. We should be careful and not make any calculation mistakes, one simple mistake can give a completely different answer.