A school choir has 80 students; 36 of them are in seventh grade. Also, 40 students in the choir are girls; 18 of them are in seventh grade. What is the probability that a student picked at random from the choir is either a girl or is in seventh grade?

A. 27/40

B. 29/40

C. 13/40

D. 33/40

Question

A school choir has 80 students; 36 of them are in seventh grade. Also, 40 students in the choir are girls; 18 of them are in seventh grade. What is the probability that a student picked at random from the choir is either a girl or is in seventh grade?

A. 27/40 

B. 29/40 

C. 13/40

D. 33/40

hero · Answer

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$$P(A) \space\text{or} \space P(B) = \frac{18}{80} + \frac{18}{80} + \frac{22}{80}$$