Question

A skin care company had 1,500 people try a new acne cream. Nine people had a mild reaction the formula is then improved and those 1,500 people try the new cream only 4

Answer 1

The percent decrease in number of allergic reactions is 55%

Explanation:

Only 4 of them had a mild allergic reaction. What is the percent decrease in number of allergic reactions?

Percent of allergic people= Allergic people/ Total people * 100

= 9/1500* 100

= 0.6 %

IT means that out of 1000 people only 6 persons are allergic to the cream.

New Percent of allergic people= Allergic people/ Total people * 100

= 4/1500* 100

= 0.267 %

It means that out of 1000 people only 2.67 persons are allergic to the new improved cream.

Difference between Percentage = Old Percentage- New Percentage

= 0.6 %- 0.267%

=0.333%

Decrease= 0.333% = 0.333/100

In every thousand people 3.33 people are free of allergic reactions from those 6 allergic people.

Percentage Decrease= Decrease/ Total * 100

= 0.333/ 0.6 *100

= 0.55*100

= 55 %

The percent decrease in number of allergic reactions is 55%