SOLUTION: A student's pencil case contains 4 pencils, 5 blue pens and 3 red pens. The student reaches in to randomly select something to write with. What is the probability that the student

Algebra ->  Probability-and-statistics -> SOLUTION: A student's pencil case contains 4 pencils, 5 blue pens and 3 red pens. The student reaches in to randomly select something to write with. What is the probability that the student       Log On


   

Question 572227: A student's pencil case contains 4 pencils, 5 blue pens and 3 red pens. The student reaches in to randomly select something to write with. What is the probability that the student selected a blue or red pen?
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
P(Blue or Red pen) = P(Blue pen) + P(Red pen)

P(Blue or Red pen) = (# of blue pens)/(# total) + (# of red pens)/(# total)

P(Blue or Red pen) = (5)/(4+5+3) + (3)/(4+5+3)

P(Blue or Red pen) = 5/12 + 3/12

P(Blue or Red pen) = 8/12

P(Blue or Red pen) = 2/3