To find the probability of selecting a red pen first, a black pen second, and another red pen third, we need to calculate the probability of each event happening and then multiply them together.

Step 1: Calculate the probability of selecting a red pen first.
There are a total of 20 pens in the box, and 7 of them are red. Therefore, the probability of selecting a red pen first is 7/20.

Step 2: Calculate the probability of selecting a black pen second.
After the first pen is selected, there are now 19 pens left in the box. Out of these, 4 are black. Therefore, the probability of selecting a black pen second is 4/19.

Step 3: Calculate the probability of selecting another red pen third.
After the first two pens are selected, there are now 18 pens left in the box. Out of these, 6 are red. Therefore, the probability of selecting another red pen third is 6/18, which simplifies to 1/3.

Step 4: Multiply the probabilities together.
To find the overall probability, we multiply the probabilities of each event together:
(7/20) * (4/19) * (1/3) = 28/1140 = 7/285.

Therefore, the probability of selecting a red pen first, a black pen second, and another red pen third is 7/285.

Question

To find the probability of selecting a red pen first, a black pen second, and another red pen third, we need to calculate the probability of each event happening and then multiply them together.

Step 1: Calculate the probability of selecting a red pen first.
There are a total of 20 pens in the box, and 7 of them are red. Therefore, the probability of selecting a red pen first is 7/20.

Step 2: Calculate the probability of selecting a black pen second.
After the first pen is selected, there are now 19 pens left in the box. Out of these, 4 are black. Therefore, the probability of selecting a black pen second is 4/19.

Step 3: Calculate the probability of selecting another red pen third.
After the first two pens are selected, there are now 18 pens left in the box. Out of these, 6 are red. Therefore, the probability of selecting another red pen third is 6/18, which simplifies to 1/3.

Step 4: Multiply the probabilities together.
To find the overall probability, we multiply the probabilities of each event together:
(7/20) * (4/19) * (1/3) = 28/1140 = 7/285.

Therefore, the probability of selecting a red pen first, a black pen second, and another red pen third is 7/285.

Knowee AI · Accepted Answer

To find the probability of selecting a red pen first, a black pen second, and another red pen third, we need to calculate the probability of each event happening and then multiply them together.

Step 1: Calculate the probability of selecting a red pen first.
There are a total of 20 pens in the box, and 7 of them are red. Therefore, the probability of selecting a red pen first is 7/20.

Step 2: Calculate the probability of selecting a black pen second.
After the first pen is selected, there are now 19 pens left in the box. Out of these, 4 are black. Therefore, the probability of selecting a black pen second is 4/19.

Step 3: Calculate the probability of selecting another red pen third.
After the first two pens are selected, there are now 18 pens left in the box. Out of these, 6 are red. Therefore, the probability of selecting another red pen third is 6/18, which simplifies to 1/3.

Step 4: Multiply the probabilities together.
To find the overall probability, we multiply the probabilities of each event together:
(7/20) * (4/19) * (1/3) = 28/1140 = 7/285.

Therefore, the probability of selecting a red pen first, a black pen second, and another red pen third is 7/285.

A box contains 9 white 4 black and 7 red pens. Three pens are selected in succession without replacement. What is the probability if the first pen is red, second is black and third is also red

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