a jar has 5 black, 8 blue, and 7 yellow marbles. a marble is chosen at random.P(yellow or blue).

Question

a jar has 5 black, 8 blue, and 7 yellow marbles.  a marble is chosen at random.P(yellow or blue).

drwls · Answer

P (y or b) = 15/20 = 3/4

Yuki · Answer

Total number of marbles in the jar is 20. If the possibility you're asking for involves BOTH yellow and blue then there's 15 yellow and blue marbles. Divide 15 by 20 and you get 3/4, which is 75% possiblity :)