Question

In an after school program, students must choose to either play on the playground or read a book silently. On one cloudy day, 70% of the students chose to play on the playground, and the rest chose read a book silently. 60% of the students who went to the playground are boys, and 20% who stayed inside to read a book are boys. If a student is randomly selected on this day, what is the probability that the student is a girl?

Answer 1

52% chance. We can simplify it by change the first set of percentages to amounts out of 100.
70% = 70 and 30% = 30. We then can multiply those numbers by our "sub"-percentages.
70 * 0.6 = 42 and 30 * 0.2 = 6.
We then convert those two amounts amounts back into percents.
42 = 42% and 6 = 6%
Adding these two we get the percent of boys.
42% + 6% = 48%
Now, to get the percent of girls we take 48% out of 100% to get our end result of 52%.