a) 468 story books

b) 460 story books

c) 408 story books

d) 466 story books

correct answer is: a) 468 story books

Explanation

Here,
The ratio of story books and other books is 4\;:\;3\;.
And, the number of story books is 1248.
Let’s,
The number of other books is ‘x’.
According to the question,
4\;:\;3\;=\;1248\;:\;x
\rightarrow\large\frac{4}{3}=\frac{1248}{x}
\rightarrow 4x=\left(1248\times3\right)
\rightarrow x=\large\frac{1248\times3}{4}
\rightarrow x=936
So that,
The number of other books is 936.

Let,
‘y’ number of story books are purchased.
Now,
\left(1248+y\right)\;:\;936\;=\;11\;:\;6
\rightarrow\large\frac{1248+y}{936}=\frac{11}{6}
\rightarrow6\left(1248+y\right)=11\times936
\rightarrow 7488+6y=10296
\rightarrow 6y=\left(10296-7488\right)
\rightarrow 6y=2808
\rightarrow y=\large\frac{2808}{6}
\rightarrow y=468
So that, 468 story books are purchased.
Ans: 468 story books are purchased.