If a shopkeeper sells 1/3 of his goods at a profit of 14%, 3/5 of the goods at a profit of 17.5% and the remaining at a profit of 20%, then his profit on the whole is equal to:

Let us assume that he had 15 items with a CP of 100 each.
The shopkeeper sells 1/3 of his goods at a profit of 14% i.e. 5 items were sold at 114 each.
He sells 3/5 of the goods at a profit of 17.5% i.e. 9 items at 117.5 each.
Remaining items = 1 and it is sold at a profit of 20% i.e. at 120.
Total SP = 5*114 + 9*117.5 + 120 = 1747.5
Total CP = 1500.
Overall profit percentage = $$\frac{1747.5-1500}{1500}\times\ 100=16.5\%$$.