In the following question, some part of the sentence may have errors. Find out which part of the sentence has an error and select the appropriate option. If a sentence is free from error, select 'No Error'.
She is walking (1)/ in the park (2)/ since morning. (3)/ No error (4)
A shopkeeper mixed two verities of rice at Rs. 40/kg and Rs.60/kg in the ratio 3: 2 and sold the mixture at 10% profit. Find the price per kg at which he sold the mixture?