Welcome to Westonci.ca, where curiosity meets expertise. Ask any question and receive fast, accurate answers from our knowledgeable community. Experience the convenience of finding accurate answers to your questions from knowledgeable professionals on our platform. Connect with a community of professionals ready to help you find accurate solutions to your questions quickly and efficiently.

There is a bag filled with 5 blue and 4 red marbles.
A marble is taken at random from the bag, the colour is noted and then it is replaced.
Another marble is taken at random.
What is the probability of getting 2 that are different in colour?


Sagot :

Answer:  40/81

===========================================

Work Shown:

B = selecting 1 blue

R = selecting 1 red

P(B) = 5/9, since there are 5 blue out of 5+4 = 9 total

P(R) = 4/9, since there are 4 red out of 9 total

P(2 blue) = P(B)*P(B) = (5/9)*(5/9) = 25/81

P(2 red) = P(R)*P(R) = (4/9)*(4/9) = 16/81

The last two equations are valid because we are sampling with replacement. Each selection is independent.

-------------------

P(2 same color) = P(2 blue OR 2 red)

P(2 same color) = P(2 blue) + P(2 red)

P(2 same color) = 25/81 + 16/81

P(2 same color) = (25+16)/81

P(2 same color) = 41/81

-------------------

P(2 different color) = 1 - P(2 same color)

P(2 different color) = 1 - 41/81

P(2 different color) = 81/81 - 41/81

P(2 different color) = (81-41)/81

P(2 different color) = 40/81