Question

12685 books were bought for the primary section, 15790 books were bought for the middle section and 13698 books were bought for the senior section of the school library. What was the total number of books bought for the library?
\[\begin{align}
  & A.42163 \\
 & B.42173 \\
 & C.42130 \\
 & D.42193 \\
\end{align}\]

Answer 1

Hint: To solve this question, we will first assume values for all given numbers of books for primary section, for secondary section and for middle section. Suppose, we have assumed above values as p, q and r. Then, the final total amount can be calculated by adding p, q and r to get the result.

Complete step-by-step answer:
Given that, 12685 books were bought for the primary section. Let this value be variable x.
\[x=12685\text{ }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. (i)}\]
Again, we are given that 15790 books were bought for the middle section. Let this value be variable y.
\[y=15790\text{ }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. (ii)}\]
Finally, we are given that 13698 books were bought for the senior section of the school library. Let this value be variable z.
\[z=13698\text{ }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. }\text{. (iii)}\]
We have to calculate the total number of books bought by the library.
That can be calculated by adding all values of number of books for primary section, number of books for middle section and number of books for senior section.
We have to add equation (i), (ii) and (iii).
The total number of books bought by the library is given by x + y + z.
Substituting value of x=12685, y=15790 and z=13698 from equation (i), (ii) and (iii) we get,
\[\begin{align}
  & x+y+z=12685+15790+13698 \\
 & \Rightarrow 28475+13698 \\
 & \Rightarrow 42173 \\
\end{align}\]
Therefore the number of books bought by the library is 42173

So, the correct answer is “Option B”.

Note: Another way to solve this question can be without assuming any variable and directly adding 12685, 15790 and 13698.
Which is given by \[\Rightarrow 12685+15790+13698=42173\] option B.
Therefore, the answer is the same.
Also, be careful while adding the terms and choose the option carefully as they are the same.