A shopkeeper believes in running his business on the sentiments of market i.e., quick response to the demand-supply relationship. He starts every morning by selling product X at Rs 500 for the first hour. If the number of customers for any hour is more than 10, he will increase the price by Rs 10 over the price of the previous hour. If less than 10, he will decrease the price by Rs 10 over the previous hour. If it is equal to 10, then he will maintain the same price level of the previous hour. CP of product X is Rs 440.
The shopkeeper never sells for a loss. If he shuts his shop after 10 hours due to this principle and there is exactly one hour when the number of customers was 10, then the minimum number of hour when the number of customers is more than 10 is