Question

. A jar contains 5 blue marbles and 7 yellow marbles. Two marbles are selected at random.

a. What is the probability that a yellow marble is drawn first?                                                         

b. What is the probability that you will draw two yellow marbles if the first marble is replaced?                                                                                                                                                  

c. What is the probability that you will draw two yellow marbles if the first marble is not replaced?            

d. What is the probability of drawing a green marble?                                                                        

Answer 1

a.

P(yellow) = no. of yellow / total

= 7 / (5+7)

= 7/12

= 0.5833

b.

P(2 yellow with repalcement) = P(yellow)*P(yellow)

= (7/12)*(7/12)

= 0.3403

c.

P(2 yellow without replacement) = (select 2 yellow)/(select 2 marbles)

= (7C2)/(12C2)   { nCx = n! / (n - x)! }

= 0.3182

d.

P(green) = no. of green/ total

= 0/12

= 0

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