If a shopkeeper buys a certain number of items for a certain sum and sells a fraction of the said number for the same amount, then his profit is 300%.What is the fraction?

\(\frac{1}{4}\)

To gain 300% profit, the Rs.100 article must be sold in Rs.400.

Therefore,

C.P. = Rs.100

S.P. = Rs.400

Profit = Rs.300

So, the fraction of part must be= \(\frac{100}{400}\) = \(\frac{1}{4}\)