Combinatorial Probability

The question asks for the probability of an event defined by a combinatorial selection process, requiring counting favorable and total outcomes.

kyotsu-test 2015 QCourse2-I-Q2 View
There are two bags, A and B. Bag A contains four white balls and one red ball, and bag B contains two white balls and three red balls. Two balls are taken simultaneously out of bag A, then two balls are taken simultaneously out of bag B.
(1) The probability that two white balls are taken out of A, and one white ball and one red ball are taken out of B is $\frac{\mathbf{O}}{\mathbf{PQ}}$.
(2) The probability that the four balls taken out consist of three white balls and one red ball is $\frac{\mathbf{R}}{\mathbf{S}}$.
(3) The probability that the four balls taken out all have the same color is $\square$ T UV
(4) The probability that of the four balls taken out, two or fewer are white balls is $\frac{\mathbf{WX}}{\mathbf{W}}$.
kyotsu-test 2016 QCourse1-I-Q2 View
In a box there are ten cards on which the numbers from 0 to 9 have been written successively. We take three cards out of the box using two methods and consider the probabilities.
(1) We take out three cards simultaneously.
(i) The probability that each number on the three cards is 2 or more and 6 or less is $\dfrac{\mathbf{KL}}{\mathbf{MN}}$.
(ii) The probability that the smallest number is 2 or less and the greatest number is 8 or more is $\dfrac { \mathbf { N O } } { \mathbf { P Q } }$.
(2) Three times we take out one card from the box, check its number, and then return it to the box. The probability that the smallest number is 2 or more and the greatest number is 6 or less is $\dfrac { \mathbf { R } } { \mathbf { S } }$.
kyotsu-test 2016 QCourse2-I-Q2 View
In a box there are ten cards on which the numbers from 0 to 9 have been written successively. We take three cards out of the box using two methods and consider the probabilities.
(1) We take out three cards simultaneously.
(i) The probability that each number on the three cards is 2 or more and 6 or less is $\dfrac{\mathbf{KL}}{\mathbf{MN}}$.
(ii) The probability that the smallest number is 2 or less and the greatest number is 8 or more is $\dfrac { \mathbf { N O } } { \mathbf { P Q } }$.
(2) Three times we take out one card from the box, check its number, and then return it to the box. The probability that the smallest number is 2 or more and the greatest number is 6 or less is $\dfrac { \mathbf { R } } { \mathbf { S } }$.
taiwan-gsat 2022 Q16 5 marks View
A bag contains blue, green, and yellow balls totaling 10 balls. Two balls are randomly drawn from the bag (each ball has an equal probability of being drawn). The probability that both balls drawn are blue is $\frac{1}{15}$, and the probability that both are green is $\frac{2}{9}$. The probability that two randomly drawn balls are of different colors is $\frac{\text{(16--1)}}{\text{(16--3)}}$. (Express as a fraction in lowest terms)
turkey-yks 2010 Q32 View
A bag contains 2 red, 2 white, and 1 yellow marble.
When 4 marbles are randomly drawn from the bag, what is the probability that the remaining marble in the bag is red?
A) $\frac { 1 } { 2 }$
B) $\frac { 2 } { 3 }$
C) $\frac { 3 } { 4 }$
D) $\frac { 2 } { 5 }$
E) $\frac { 3 } { 5 }$
turkey-yks 2011 Q19 View
From a group of 6 girls and 7 boys, 2 representatives are selected.
What is the probability that one of the two selected representatives is a girl and the other is a boy?
A) $\frac { 3 } { 4 }$
B) $\frac { 3 } { 8 }$
C) $\frac { 2 } { 13 }$
D) $\frac { 7 } { 13 }$
E) $\frac { 9 } { 13 }$
turkey-yks 2012 Q22 View
A bag contains 5 red and 4 white marbles.
When 3 marbles are drawn randomly from this bag at the same time, what is the probability that there are at most 2 marbles of each color?
A) $\frac { 2 } { 3 }$
B) $\frac { 3 } { 4 }$
C) $\frac { 5 } { 6 }$
D) $\frac { 7 } { 8 }$
E) $\frac { 8 } { 9 }$
turkey-yks 2015 Q14 View
Four identical matches are taken, each with only one flammable end. These matches are randomly arranged along all sides of a square whose side length is the same as the length of one match, with the ends touching each other.
What is the probability that there are no flammable ends in contact with each other in this arrangement?
A) $\frac { 1 } { 4 }$
B) $\frac { 1 } { 8 }$
C) $\frac { 3 } { 8 }$
D) $\frac { 1 } { 16 }$
E) $\frac { 3 } { 16 }$
turkey-yks 2020 Q26 View
An exam consisting of a total of 8 questions, with 4 questions each in the verbal and quantitative sections, has the following statement in its booklet: ``To pass the exam, you must answer at least 5 questions correctly in total, with at least 2 questions from each of the verbal and quantitative sections.'' Sevcan, who read this statement incompletely, randomly selected 5 out of 8 questions on the exam and answered each question she selected correctly.
Accordingly, what is the probability that Sevcan passes the exam?
A) $\frac{3}{4}$
B) $\frac{4}{5}$
C) $\frac{5}{6}$
D) $\frac{6}{7}$
E) $\frac{7}{8}$
turkey-yks 2020 Q29 View
Kerem randomly selects 3 numbers using the buttons shown in the figure to create the password for his locker, such that each is in a different row and different column.
Accordingly, what is the probability that all of the numbers Kerem selected are odd?
A) $\frac{1}{2}$
B) $\frac{1}{3}$
C) (from figure)
D) $\frac{5}{9}$
E) $\frac{4}{27}$