Abag contains 12 red marbles, 5 yellow marbles, and 15 green marbles. how many additional red marbles must be added to the 32 marbles already in the bag so that the probability of randomly drawing a red marble is ? select your answer. 13 18 28 32 40

= 18 red marbles

Step-by-step explanation:

Let x be the number of red marbles that must be added

Therefore;

New number or red marbles = x+12

Total marbles will be x+32

Thus;

The probability of selecting a red marble = (x+12)/(x+32)

Therefore;

(x+12)/(x+32)=3/5

5(x+12)=3(x+32)

5x+60+3x+96

2x=36

x=18

b) the dogs need to shift their focus to human scent.

the probability is 0