?
An urn contains 6 red, 5 blue and 2 green marbles. If three marbles are picked at random, what is the probability that at least one is blue?
Answer & Solution
Correct Answer:
Option
D
P(None is blue),
$$\eqalign{ & = \frac{{^8{C_3}}}{{^{13}{C_3}}} \cr & = \frac{{56}}{{286}} \cr & = \frac{{28}}{{143}} \cr} $$
P(At least one is blue),
$$\eqalign{ & = 1 - \frac{{28}}{{143}} \cr & = \frac{{115}}{{143}} \cr} $$
$$\eqalign{ & = \frac{{^8{C_3}}}{{^{13}{C_3}}} \cr & = \frac{{56}}{{286}} \cr & = \frac{{28}}{{143}} \cr} $$
P(At least one is blue),
$$\eqalign{ & = 1 - \frac{{28}}{{143}} \cr & = \frac{{115}}{{143}} \cr} $$
Join the Discussion
Login to post a comment or share your explanation.
Login