Algebra Question

Question

 

0854

 

 

Only tenth,eleventh,and twelfth grade students attend Washington High School. The ratio of tenth graders to the school's total student population is 86:255 and the ration of eleventh graders to the school's total student population is 18:51. If 1 student is chosen at random from the entire school which grade is that student most likely to be in

 

A) tenth

 

B) Eleventh

 

C) Twelfth

 

D) All Grades

 

E)Can not be determined

 

Any help will greatly be appreciated. I thought I had the right answer however I obviously don't. THANK YOU

Answer 1

The ratio of tenth graders to the school's total population is 86:255 = 33.7%.

The ratio of eleventh graders to the school's total population is 18:51 = 35.3%.

Since the probability of a student being in either tenth, eleventh, or twelfth grade = 1 = 100% (that is, certainty), then the probability of a randomly drawn student being in twelfth grade is (100-33.7-35.3)% = 31.0%.

 

When randomly choosing one student from the whole school, it is most likely (35.3%) that the student is in the eleventh grade.