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1.

On a true-false quiz of six questions, Karen answers all the questions.

What is the probability that she answers the first three questions correctly and the last three questions incorrectly?

 

1/4

1/8

1/64

1/32

 

2.

 

 

A bag contains 5 red marbles and 4 green marbles.

What is the probability of choosing a red marble then a green marble, without replacement?

 

20/81

5/18

25/72

 

Thank you!!

25/81

 Apr 22, 2019
 #1
avatar+103069 
+2

1.

On a true-false quiz of six questions, Karen answers all the questions.

What is the probability that she answers the first three questions correctly and the last three questions incorrectly?

 

These are independent events....the probability of answering any question correctly or incorrectly is 1/2

 

So.....  (1/2)^3 * (1/2)^3  =  (1/2)^6  =  1/64

 

 

cool cool cool

 Apr 22, 2019
 #2
avatar+103069 
+2

2.  A bag contains 5 red marbles and 4 green marbles.

What is the probability of choosing a red marble then a green marble, without replacement?

 

Prob red  =  (5/9)

Prob green (once red is selected)  = 4/8  =  1/2

Total probability  =  (5/9)(1/2)   =  5 / 18

 

 

cool cool cool

 Apr 22, 2019
 #4
avatar+381 
0

Thank you so much for the help CPhill!!!

PhoenixForever  Apr 23, 2019
 #3
avatar+128 
-1

For the first one...

 

To calculate the first problem, first find the probability of getting one right. That is 1/2. Then, getting three right is the same as 1/8 probability. Likewise, getting three wrong is 1/8 probability. Multiplying these two fractions gets us 1/64 probability.

 

The probability of Karen getting three questions right and three questions wrong is 1/64.

 

~~Hypotenuisance

 Apr 23, 2019

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