Probability

Question

Julia put some marbles into  box. She put in 7 gray marbles, 3 black marbles, 2 red marbles, 4 orange marbles, and 1 brown marble. Ellie reaches into the box and removes 1 marble without looking. What is the probability that she selects a marble that is either black or brown?

Answer 1

there are 7+3+2+4+1=17 marbles

there are 4 marbles that are either black (3) or brown (1)

the probability is 4/17

another way...

probability of a black marble +probability of a brown marble

3/17+1/17=4/17 because of the word "or"