A bag contains only red, green, brown and yellow marbles.

The probabilities of selecting each colour are shown below.
The probability of choosing a red marble is the same as choosing a yellow marble.

Colour Red Green Brown Yellow
Probability 0.4 0.28
Find the probability of selecting a brown or yellow marble.

To find the probability of selecting a brown or yellow marble, we need to add the probabilities of selecting a brown marble and a yellow marble.

Given that the probability of selecting a yellow marble is the same as selecting a red marble, we can assume that the probability of selecting each is equal. So, the probability of selecting a yellow marble is 0.4.

Now we need to find the probability of selecting a brown marble, which is given as 0.28.

To find the probability of selecting a brown or yellow marble, we add the probabilities:

0.4 (probability of selecting a yellow marble) + 0.28 (probability of selecting a brown marble)
= 0.68

Therefore, the probability of selecting a brown or yellow marble is 0.68.

To find the probability of selecting a brown or yellow marble, we need to add the individual probabilities of selecting a brown marble and a yellow marble.

Given the information provided, we are only given the probability of selecting a brown marble, which is 0.28. However, the probability of selecting a yellow marble is not given explicitly, but it is stated that the probability of choosing a red marble is the same as choosing a yellow marble.

Let's denote the probability of selecting a yellow marble as P(Y). We know that P(Red) = P(Yellow).

Since the only missing probability is for the yellow marble, we can set up an equation using the information provided:

P(Brown) + P(Yellow) = 1
0.28 + P(Yellow) = 1

We can solve this equation to find the probability of selecting a yellow marble:

P(Yellow) = 1 - 0.28
P(Yellow) = 0.72

Now, we can find the probability of selecting a brown or yellow marble by adding the probabilities of selecting them individually:

P(Brown or Yellow) = P(Brown) + P(Yellow)
P(Brown or Yellow) = 0.28 + 0.72
P(Brown or Yellow) = 1

Therefore, the probability of selecting a brown or yellow marble is 1 or 100%.

let's complete you table

Red Gr Br Yll
0.4 0.28 x 0.4 , but they must add up to 1, so x = .08