Question

A jar contains 4 red marbles, 3 white marbles, and 4 blue marbles. Two marbles are randomly selected from the jar with replacement. Find the following probabilities. Leave your answer as a reduced fraction.

A red marble and then a blue marble is randomly selected.

A white marble and then a red marble is randomly selected.

Answer 1

Solution:
Given: A jar contains

4 red marbles,

3 white marbles, and

4 blue marbles.

Total Marbles = 11

Two marbles are randomly selected from the jar with replacement.

Part a) Find:

P( A red marble and then a blue marble ) =...............?

P( Red and Blue) =............?

Since we are replacing first selected marble in jar, total marbles remains same and selection is independent .

Thus

P( Red and Blue) =P(First Red) X P(Second Blue)

Part b) Find:

P( A White marble and then a Red marble ) =...............?

P( White and Red) =............?

P( White and Red) = P( First White) X P(Second Red)