A marble is drawn at random from the bag. The bag contains 3 green, 4 yellow, 5 blue, and 8 pink marbles. What is the probability that the marble drawn is a green or blue?

First find the total number of marbles.

3 + 4 + 5 + 8 = 20 marbles

to find a probability l, put your sample quantity as the numerator and the total number of marbles as your denominator

3/20 for green marbles and 5/20 for blue marbles

any fraction that is not in simplest terms, yet, needs to be simplified.

5/20 - - - > 1/4 for blue marbles and 3/20 for green marbles

then write out the probability ...

1 to 4 marbles and 3 to 20 marbles (or your can keep it as a fraction or write it as 1:4 and 3:20)

don't forget to label your answer too

if it is looking for altogether the probability then you add both your probabilities and simplify it

Probability=number of specific outcomes/total number of possible outcomes ...

P (GorB) = P (G) + P (B)

P (GorB) = 3/20+5/20

P (GorB) = 8/20=2/5 (40%)