a bag contains 5 green marbles 2 white marbles 8 blue marbles 9 red marbles and 6 black marbles what is the probability of drawing a white marble replacing it and then drawing a green marble? Answer choices A 1/6 B 1/15 C 1/87 D 1/90 I think its D, but I am not sure and how did you do this question
Pr(w,g)=2/30*5/30=1/15*1/6=1/90 You think correctly.
2/30*5/29
10/870
1/87
To find the probability of drawing a white marble, replacing it, and then drawing a green marble, we need to calculate the individual probabilities of each event.
First, let's calculate the probability of drawing a white marble.
The bag contains a total of 5 green marbles, 2 white marbles, 8 blue marbles, 9 red marbles, and 6 black marbles. Hence, the total number of marbles in the bag is 5 + 2 + 8 + 9 + 6 = 30.
Therefore, the probability of drawing a white marble is 2/30 = 1/15.
Now, since we are replacing the white marble back into the bag, the number of white marbles remains the same at 2, and the total number of marbles in the bag also remains the same at 30.
Next, let's calculate the probability of drawing a green marble after replacing the white marble.
The bag initially contains 5 green marbles, so the probability of drawing a green marble is 5/30 = 1/6.
To calculate the probability of both events happening, we multiply the individual probabilities:
P(white marble and green marble) = P(white marble) * P(green marble after replacing white marble)
= (1/15) * (1/6)
= 1/90
Therefore, the correct answer is D, 1/90.
For such problems, you can follow this general approach to calculate probabilities by dividing the number of favorable outcomes by the total number of possible outcomes.