A jar had 16 marbles 4 are red . One marble is drawn and not replaced. Then s second marble is drawn . What is the probability of selecting a red marble and then another red marble?
To find the probability of selecting a red marble and then another red marble, we need to use the concept of conditional probability. The conditional probability is the probability of an event occurring given that another event has already occurred.
In this case, we need to calculate the probability of drawing a red marble first, and then, assuming the first marble was red, the probability of drawing another red marble.
Let's break down the steps to find the answer:
Step 1: Calculate the probability of drawing a red marble first.
Since there are 4 red marbles out of 16 total marbles, the probability of drawing a red marble first is 4/16 or 1/4.
Step 2: Calculate the probability of drawing another red marble, assuming the first was red.
Since one marble was drawn and not replaced, there are now 15 marbles left, and the number of red marbles has decreased to 3. Therefore, the probability of drawing another red marble, assuming the first was red, is 3/15 or 1/5.
Step 3: Multiply the conditional probabilities.
To find the probability of both events occurring, we multiply the probabilities from step 1 and step 2.
(1/4) * (1/5) = 1/20
Therefore, the probability of selecting a red marble and then another red marble is 1/20.