In a company that makes hair-care products, if 3,000 people try a new shampoo and 12 people had a mild allergic reaction, the percentage of people that had mild allergic reaction can be expressed as;
Number of people allergic/total people that tried a new shampoo × 100%
= 12/3000×100
= 1200/3000
= 0.4%
This shows that 0.4% of the people had a mild allergic reaction
