Question

A man purchased a box full of pencils at the rate of $7$ for Rs. $9$ and sold all of them at the rate of $8$ for Rs. $11$.In this transaction he gained Rs. $10$. How many pencils did the box contain ?

• A. 100
• B. 112
• C. 114
• D. 115

Answer 1

The correct option is B 112

Suppose the number of pencils bought $=$ L.C.M of $7$ and $8=56$.
C.P of $7$ Pencils $=$ Rs. $9$
Then, C.P of $56$ pencils $=(\frac{9}{7}\times 56)=72$
S.P of $8$ pencils $=$ Rs. $11$
Then, S.P of $56$ pencils $=(\frac{11}{8}\times 56)=77$
So, amount gained on $56$ pencils $=77-72=5$
Now, Rs. $5$ are gained on $56$ pencils
So, Rs. $10$ are gained on $(\frac{56}{5}\times 10)=112$ pencils.