Question

Ali surveyed 200 students at a school and recorded the eye color and the gender of each student. of the 80 male students who were surveyed, 60 had brown eyes. if eye color and gender are independent, how many female students surveyed would be expected to have brown eyes?

Answer 1

Total number of students surveyed = 200
Number of male students = 80
Number of female students = 200 - 80 = 120

Number of brown eyed male students = 60
Probability of a brown eyed male student = 60 / 80 = 0.75.

Since, eye color and gender are independent, this means that eye color is not affected by the gender. Thus, we expect a similar probability of brown eye for female as we had for male.

Let the number expected of brown eyed females be x, then x / 120 = 0.75.

Thus, x = 120(0.75) = 90.

Therefore, the number female students surveyed expected to be brown eyed is 90.