SOLUTION: there are 90 students , 60 play clarinet and 40 play the trombone, 10 only play the trombone. find the probability of a student playing the trombone or the clarinet.

Algebra ->  Probability-and-statistics -> SOLUTION: there are 90 students , 60 play clarinet and 40 play the trombone, 10 only play the trombone. find the probability of a student playing the trombone or the clarinet.      Log On


   

Question 429619: there are 90 students , 60 play clarinet and 40 play the trombone, 10 only play the trombone. find the probability of a student playing the trombone or the clarinet.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

there are 90 students , 60 play clarinet and 40 play the trombone, 

10 only play the trombone: that is 30 play both.

P(trombone or clarinet) = 40/90 + 60/90 - 30/90 = 70/90 = 7/9



P(A or B) = P(A) + P(B) - P(A and B)