Statistics

Question

A jar contains 10 blue marbles, 5 red marbles, 4 green marbles, and 1 yellow marble. Two marbles are chosen (without replacement).

(a) What is the probability that one will be green and the other red?

(b) What is the probability that one will be blue and the other yellow?

Answer 1

(a) green 4/20, or 1/5, then

      red 5/19, for both

      20/380, or 1/19

 

(b) blue 10/20, or 1/2, then

     yellow 1/19, for both

     10/380, or 1/38 

  

Answer 2

Hi Tanea,

 

a) Two marbles are chosen one by one.total no of marbles = 20

    Probability of one marble chosen will be Green = P(G) =4/20

    other marble will be chosen without replacement so now total no of marbles will be 19, 

    P(R) =5/19

 

    P ( one will be Green & other Red) = 4/20 * 5/19 =1/19

 

b) Probability that one marble chosen will be blue =P(B) =10/20  

    Probability that other marble chosen will be yellow= P( Y) =1/19

 

   P( one marble will be blue & other will be yellow) = 10/20*1/19 =1/38.