Question

A bag contains 3 red, 4 yellow, and 5 blue marbles. Two marbles are randomly selected from the bag with replacement. What is the probability that:
a) Both are blue
b) They have the same color
c) At least one is red
d) Exactly one is yellow?​

Answer 1

Answer:

answer d is correct ..

( d ) Exactly one is yellow

Answer 2

Answer:

Total number of marbles is 12(3 red,4 yellow and 5 blue).2 marbles are selected randomly.

a) Probability that both are blue:

$\frac{5}{12} * \frac{4}{11 } = \frac{5}{33}$

b)Probability that they have same colour:

This means probability(both are red) +probability(both are yellow)+probability(both are blue)

$= (\frac{3}{12} * \frac{2}{11} ) + (\frac{4}{12} * \frac{3}{11} ) + (\frac{5}{12} * \frac{4}{11} )$ = $\frac{19}{66}$

c) Probability at leastone is red:

 = 1 - probability that neither is red

 $= 1 - (\frac{9}{12} * \frac{8}{11} ) = \frac{5}{11}$

d) Probability that exactly one is yellow:

 $\frac{4}{12} * \frac{8}{11} =\frac{8}{33}$