Answer:
Question:
A bag with 2 blue (B), 4 red (R) and 5 green (G) marbles (total 11 marbles).
Two are drawn at random without replacement.
Find probability of getting two marbles of same colour.
Solution:
We can get either 2B, 2R or 2G as successful outcomes.
To get two blue marbles (2B),
probability of the first one being blue = P(B)=2/11
probability of the second blue marble = P(-B)=1/10 (one left out of 10 left)
Probability that both are blue (use multiplication rule)
P(2B)=(2/11)(1/10)=2/110
Similarly, for two red marbles
P(2R)=(4/11)(3/10)=12/110
and for two green marbles
P(2G)=(5/11)(4/10)=20/110
Since all three events 2B, 2R and 2G are mutually exclusive, the probability
that any one can happen is the sum of the individual probabilities, thus
probability of getting two marbles of the same colour (without replacement)
=P(2B)+P(2R)+P(2G)
=2/110 + 12/110 + 20/110
=34/110
= 17/55
Step-by-step explanation:
