Question

In a survey, 150 high school students were asked whether they play sports. The survey also recorded the grade of each of the participants. The responses are given below: Yes No Freshman 19 22 Sophomore 23 17 Junior 18 12 Senior 20 19 Use this table to determine each of the following probabilities. Write each answer as a percent rounded to one decimal place, i.e. 16.8%. Do not include the percent symbol.

a) Find the probability that a randomly selected student is a Junior. %

b) Find the probability that a randomly selected student plays sports, i.e answered "Yes". %

c) Find the probability that a randomly selected student answered "Yes" given that they are a Junior. %

d) Find the probability that a randomly selected student answered "No" or is a Sophomore. %

Answer 1

	yes	no	total
Freshman	19	22	41
Sophomore	23	17	40
Junior	18	12	30
Senior	20	19	39
total	80	70	150

a)

probability that a randomly selected student is a Junior =(30/150)*100 =20 %

B)

probability that a randomly selected student plays sports, i.e answered "Yes". =(80/150)*100

=53.3 %

c)

probability that a randomly selected student answered "Yes" given that they are a Junior.

=(18/30)*100 =60.0 %

d)

probability that a randomly selected student answered "No" or is a Sophomore.

=(70+23)*100/150 =62.0 %