Question

After-school activities at a large high school can be classified into three types: athletics, fine arts and other. The following table gives the number of students participating in each of these types of activities by grade. Assume that students only participate in one after-school activity. Where appropriate, round to three decimals (i.e. 0.123).

	9th	10th	11th	12th	Total
Athletics	120	145	160	175	600
Fine Arts	90	100	85	125	400
Other	110	155	155	180	600
Total	320	400	400	480	1600

What is the probability a student is in 11^th grade? Answer

What is the probability that a student is in Fine Arts and is in 10th grade?  Answer

What is the probability that a student is in one of the Other school activities or 12th grade? Answer

What is the probability that a student is in Athletics given that they are in 11th grade? Answer

Are being in Other school activities and 10th grade independent events?

independent

dependent

can't tell

Are being in Athletics and 9th grade independent events?

independent

dependent

can't tell

Answer 1

1) probability a student is in 11^th grade=400/1600 =0.25

2) probability that a student is in Fine Arts and is in 10th grade =100/1600 =0.0625~0.063

3) probability that a student is in one of the Other school activities or 12th grade

=(600+480-180)/1600 =0.5625 ~0.563

4)

probability that a student is in Athletics given that they are in 11th grade =160/400 =0.25

Are being in Other school activities and 10th grade independent events? :dependent

Are being in Athletics and 9th grade independent events? : independent