Pearson Geometry Common Core, 2011
PG
Pearson Geometry Common Core, 2011 View details
5. Probability Models
Continue to next subchapter

Exercise 18 Page 853

How many females participated in the academic competition? How many of them are freshmen?

1/4

Practice makes perfect
The probability that an event will occur, given that another event has already occurred, is called a conditional probability. Since we want to know the conditional probability of selecting a freshman student given that she is a female, let's highlight the number of female freshmen and the total number of females in the given two-way frequency table.
Male Female Totals
Freshmen 3 5 8
Sophomores 6 4 10
Juniors 7 5 12
Seniors 4 6 10
Totals 20 20 40

The condition that the student selected is a female limits the total outcomes to the 20 females. Of those 20 students, 5 are freshmen. P(Freshman | Female)&=Female freshmen/Female [1em] P(Freshman | Female)&=5/20=1/4