Using the percentage concept, it is found that 0.2% of the people had a mild allergic reaction.
The percentage of an amount a over a total amount b is given by a multiplied by 100% and divided by b, that is:
[tex]P = \frac{a}{b} \times 100\%[/tex]
In this problem, 12 out of 6000 people had a reaction, hence:
[tex]P = \frac{12}{6000} \times 100\% = 0.2\%[/tex]
0.2% of the people had a mild allergic reaction.
More can be learned about the percentage concept at https://brainly.com/question/10491646