A trader sells pulses at a 32% profit and uses weights 20% less than the actual measure. Find his gain percentage.

The correct answer is 65%.

To find the trader's total gain percentage, we can analyze the cost price and the selling price based on a standard unit of weight.

Let us assume that the cost price (CP) of 1000 grams of pulses is 1000 units. Thus, the CP of 1 gram is 1 unit.

First, let's find the selling price (SP) that the trader sets. The trader sells the pulses at a 32% profit on the cost price of the actual measure he claims to sell (1000 grams):

$\mathrm{SP}=1000\times \left(1+\frac{32}{100}\right)=1320\text{units}$

So, the trader charges the customer 1320 units for a claimed 1000 grams of pulses.

Second, let's determine the actual quantity of pulses the trader delivers. Since he uses weights that are 20% less than the actual measure, the delivered quantity is:

$\text{Actual quantity delivered}=1000\text{grams}\times \left(1-\frac{20}{100}\right)=800\text{grams}$

Now, let's calculate the cost price of this delivered quantity to the trader. Since 1 gram costs 1 unit, the cost of 800 grams is:

$\text{Effective Cost Price (CP)}=800\text{units}$

Therefore, the trader is selling goods that cost him 800 units for a price of 1320 units.

We can now calculate the total profit made by the trader:

$\text{Profit}=\text{Selling Price}-\text{Effective Cost Price}$

$\text{Profit}=1320-800=520\text{units}$

Finally, we calculate the gain percentage based on the effective cost price of the goods delivered:

$\text{Gain Percentage}=\left(\frac{\text{Profit}}{\text{Effective Cost Price}}\right)\times 100$

$\text{Gain Percentage}=\left(\frac{520}{800}\right)\times 100$

$\text{Gain Percentage}=0.65\times 100=65\%$

Thus, the trader's total gain percentage is 65%.