7. (10 points) Xiao Ming is preparing to make dumplings. He added 5 kilograms of water to 1.5 kilograms of flour and found the dough too runny. His grandmother told him that the dough for making dumplings should be mixed with 3 parts flour and 2 parts water. So, Xiao Ming added the same amount of flour three times, and finally, the dough was mixed as required. How many kilograms of flour did he add each time? $\qquad$ kilograms of flour.
7. (10 points) Xiao Ming is preparing to make dumplings. He added 5 kilograms of water to 1.5 kilograms of flour and found the dough too runny. His grandmother told him that the dough for dumplings should be mixed in a ratio of 3 parts flour to 2 parts water. So, Xiao Ming added the same amount of flour three times, and finally, the dough was mixed as required. How much flour did he add each time? 
【Solution】Solution: According to the analysis, since the ratio of flour to water is $3: 2$, that is, for every part of water, $3 \div 2=1.5$ parts of flour are needed. With 5 kilograms of water, the required amount of flour is: $5 \times 1.5=7.5$ kilograms. The current amount of flour is: 1.5 kilograms, so he still needs to add: $7.5-1.5=6$ kilograms. Adding it in three parts, he needs to add: $6 \div 3=2$ kilograms each time. Therefore, the answer is: 2.