Question

a man buys a plot of land at Rs360000.He sells 1/3 of the plot at a loss of 20%.Again he sells 2/3of the plot of left at a profit of 25%.At what price should he sell the remaining plot in order to get a profit of 10% on the whole?

Answer 1

First Method
CP = 3600000.
To gain 10% on whole land, SP = 360000 + 10% of 360000 = Rs. 396000.
1/3 of the land sold on 20% loss.
SP of 1/3 land = (360000/3) - 20% of (360000/3) = Rs. 96000.
SP of 2/5 of the land = (360000 * 2)/5 + 25% of (360000*2)/5 = Rs. 180000.
Thus, SP of the remaining land = 396000 - 96000 - 180000 = Rs. 120000.

Second Method

SP of total agricultural field at a profit of 10% = (360000*110)/100 = Rs. 396000.
So, SP of 1/3 of field = (360000/3)*(80/100) = Rs. 96000.
SP of 2/5th of the field =(2*360000*125)/(5*100) = Rs. 180000.
Hence, 
SP of the remaining field = Rs. (396000-96000-180000).
= Rs. 120000.