There are 10 marbles in a bag. $6$ are red and $4$ are blue. You must chose at least 1 red marble. In how many ways can you chose three total marbles.
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I thought the answer is $^9C_2$ since the first (red) marble didn't count. You have to pick a red marble which reduces the total count from 10 to 9. The answer is 116 possible ways.
probability permutations combinations
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I thought the answer is $^9C_2$ since the first (red) marble didn't count. You have to pick a red marble which reduces the total count from 10 to 9. The answer is 116 possible ways.
probability permutations combinations
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â Michael Rozenberg
Aug 10 at 9:37
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up vote
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up vote
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down vote
favorite
I thought the answer is $^9C_2$ since the first (red) marble didn't count. You have to pick a red marble which reduces the total count from 10 to 9. The answer is 116 possible ways.
probability permutations combinations
I thought the answer is $^9C_2$ since the first (red) marble didn't count. You have to pick a red marble which reduces the total count from 10 to 9. The answer is 116 possible ways.
probability permutations combinations
edited Aug 10 at 0:50
Key Flex
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asked Aug 9 at 22:35
user9995331
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Why someone wants to close this interesting topic? Explain please your step.
â Michael Rozenberg
Aug 10 at 9:37
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Why someone wants to close this interesting topic? Explain please your step.
â Michael Rozenberg
Aug 10 at 9:37
Why someone wants to close this interesting topic? Explain please your step.
â Michael Rozenberg
Aug 10 at 9:37
Why someone wants to close this interesting topic? Explain please your step.
â Michael Rozenberg
Aug 10 at 9:37
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4 Answers
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There are total of $10$ balls in which $6$ are red and $4$ are blue.
First you can choose $1$ Red and $2$ blue in $dbinom61dbinom42=36$ ways
Second you can choose $2$ Red and $1$ blue in $dbinom62dbinom41=60$ ways
Third you can choose all $3$ red in $dbinom63=20$ ways
In total you can choose in $dbinom61dbinom42+dbinom62dbinom41+dbinom63=36+60+20=116$ ways
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The overall numbers of ways to choose 3 marbles are
$$N_1=binom103=120$$
The overall numbers of ways to choose 3 blue marbles are
$$N_2=binom43=binom41=4$$
therefore $N=N_1-N_2=116$.
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up vote
4
down vote
Hint: In how many ways can you choose three marbles, none of which are red?
2
4 C 3 would be picking all blue. Total number is 10 C 3. Take the difference?
â user9995331
Aug 9 at 22:53
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up vote
4
down vote
you want to choose three marbles and must choose at least a red marble.
Here are the ways in you can do that
1Red 2Blue
2Red 1Blue
3Red
$$total=binom61binom42+binom62binom41+binom63=116 ways$$
Why do you need to account for the 'other' possibilities the chose function is implied? The ball is either red or blue. I am confused why you multiply them in this instance.
â user9995331
Aug 9 at 23:17
you need to choose three balls but you also want to choose at least 1 read thus every time you need to choose a red with blue balls possibilities are 1red and 2 blue balls , 2 red and 1 blue balls , 3 red balls
â Deepesh Meena
Aug 9 at 23:18
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4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
5
down vote
accepted
There are total of $10$ balls in which $6$ are red and $4$ are blue.
First you can choose $1$ Red and $2$ blue in $dbinom61dbinom42=36$ ways
Second you can choose $2$ Red and $1$ blue in $dbinom62dbinom41=60$ ways
Third you can choose all $3$ red in $dbinom63=20$ ways
In total you can choose in $dbinom61dbinom42+dbinom62dbinom41+dbinom63=36+60+20=116$ ways
add a comment |Â
up vote
5
down vote
accepted
There are total of $10$ balls in which $6$ are red and $4$ are blue.
First you can choose $1$ Red and $2$ blue in $dbinom61dbinom42=36$ ways
Second you can choose $2$ Red and $1$ blue in $dbinom62dbinom41=60$ ways
Third you can choose all $3$ red in $dbinom63=20$ ways
In total you can choose in $dbinom61dbinom42+dbinom62dbinom41+dbinom63=36+60+20=116$ ways
add a comment |Â
up vote
5
down vote
accepted
up vote
5
down vote
accepted
There are total of $10$ balls in which $6$ are red and $4$ are blue.
First you can choose $1$ Red and $2$ blue in $dbinom61dbinom42=36$ ways
Second you can choose $2$ Red and $1$ blue in $dbinom62dbinom41=60$ ways
Third you can choose all $3$ red in $dbinom63=20$ ways
In total you can choose in $dbinom61dbinom42+dbinom62dbinom41+dbinom63=36+60+20=116$ ways
There are total of $10$ balls in which $6$ are red and $4$ are blue.
First you can choose $1$ Red and $2$ blue in $dbinom61dbinom42=36$ ways
Second you can choose $2$ Red and $1$ blue in $dbinom62dbinom41=60$ ways
Third you can choose all $3$ red in $dbinom63=20$ ways
In total you can choose in $dbinom61dbinom42+dbinom62dbinom41+dbinom63=36+60+20=116$ ways
edited Aug 9 at 22:52
answered Aug 9 at 22:45
Key Flex
1
1
add a comment |Â
add a comment |Â
up vote
5
down vote
The overall numbers of ways to choose 3 marbles are
$$N_1=binom103=120$$
The overall numbers of ways to choose 3 blue marbles are
$$N_2=binom43=binom41=4$$
therefore $N=N_1-N_2=116$.
add a comment |Â
up vote
5
down vote
The overall numbers of ways to choose 3 marbles are
$$N_1=binom103=120$$
The overall numbers of ways to choose 3 blue marbles are
$$N_2=binom43=binom41=4$$
therefore $N=N_1-N_2=116$.
add a comment |Â
up vote
5
down vote
up vote
5
down vote
The overall numbers of ways to choose 3 marbles are
$$N_1=binom103=120$$
The overall numbers of ways to choose 3 blue marbles are
$$N_2=binom43=binom41=4$$
therefore $N=N_1-N_2=116$.
The overall numbers of ways to choose 3 marbles are
$$N_1=binom103=120$$
The overall numbers of ways to choose 3 blue marbles are
$$N_2=binom43=binom41=4$$
therefore $N=N_1-N_2=116$.
edited Aug 9 at 22:48
answered Aug 9 at 22:43
gimusi
69.4k73685
69.4k73685
add a comment |Â
add a comment |Â
up vote
4
down vote
Hint: In how many ways can you choose three marbles, none of which are red?
2
4 C 3 would be picking all blue. Total number is 10 C 3. Take the difference?
â user9995331
Aug 9 at 22:53
add a comment |Â
up vote
4
down vote
Hint: In how many ways can you choose three marbles, none of which are red?
2
4 C 3 would be picking all blue. Total number is 10 C 3. Take the difference?
â user9995331
Aug 9 at 22:53
add a comment |Â
up vote
4
down vote
up vote
4
down vote
Hint: In how many ways can you choose three marbles, none of which are red?
Hint: In how many ways can you choose three marbles, none of which are red?
answered Aug 9 at 22:43
rogerl
16.6k22745
16.6k22745
2
4 C 3 would be picking all blue. Total number is 10 C 3. Take the difference?
â user9995331
Aug 9 at 22:53
add a comment |Â
2
4 C 3 would be picking all blue. Total number is 10 C 3. Take the difference?
â user9995331
Aug 9 at 22:53
2
2
4 C 3 would be picking all blue. Total number is 10 C 3. Take the difference?
â user9995331
Aug 9 at 22:53
4 C 3 would be picking all blue. Total number is 10 C 3. Take the difference?
â user9995331
Aug 9 at 22:53
add a comment |Â
up vote
4
down vote
you want to choose three marbles and must choose at least a red marble.
Here are the ways in you can do that
1Red 2Blue
2Red 1Blue
3Red
$$total=binom61binom42+binom62binom41+binom63=116 ways$$
Why do you need to account for the 'other' possibilities the chose function is implied? The ball is either red or blue. I am confused why you multiply them in this instance.
â user9995331
Aug 9 at 23:17
you need to choose three balls but you also want to choose at least 1 read thus every time you need to choose a red with blue balls possibilities are 1red and 2 blue balls , 2 red and 1 blue balls , 3 red balls
â Deepesh Meena
Aug 9 at 23:18
add a comment |Â
up vote
4
down vote
you want to choose three marbles and must choose at least a red marble.
Here are the ways in you can do that
1Red 2Blue
2Red 1Blue
3Red
$$total=binom61binom42+binom62binom41+binom63=116 ways$$
Why do you need to account for the 'other' possibilities the chose function is implied? The ball is either red or blue. I am confused why you multiply them in this instance.
â user9995331
Aug 9 at 23:17
you need to choose three balls but you also want to choose at least 1 read thus every time you need to choose a red with blue balls possibilities are 1red and 2 blue balls , 2 red and 1 blue balls , 3 red balls
â Deepesh Meena
Aug 9 at 23:18
add a comment |Â
up vote
4
down vote
up vote
4
down vote
you want to choose three marbles and must choose at least a red marble.
Here are the ways in you can do that
1Red 2Blue
2Red 1Blue
3Red
$$total=binom61binom42+binom62binom41+binom63=116 ways$$
you want to choose three marbles and must choose at least a red marble.
Here are the ways in you can do that
1Red 2Blue
2Red 1Blue
3Red
$$total=binom61binom42+binom62binom41+binom63=116 ways$$
edited Aug 9 at 22:53
answered Aug 9 at 22:46
Deepesh Meena
2,678720
2,678720
Why do you need to account for the 'other' possibilities the chose function is implied? The ball is either red or blue. I am confused why you multiply them in this instance.
â user9995331
Aug 9 at 23:17
you need to choose three balls but you also want to choose at least 1 read thus every time you need to choose a red with blue balls possibilities are 1red and 2 blue balls , 2 red and 1 blue balls , 3 red balls
â Deepesh Meena
Aug 9 at 23:18
add a comment |Â
Why do you need to account for the 'other' possibilities the chose function is implied? The ball is either red or blue. I am confused why you multiply them in this instance.
â user9995331
Aug 9 at 23:17
you need to choose three balls but you also want to choose at least 1 read thus every time you need to choose a red with blue balls possibilities are 1red and 2 blue balls , 2 red and 1 blue balls , 3 red balls
â Deepesh Meena
Aug 9 at 23:18
Why do you need to account for the 'other' possibilities the chose function is implied? The ball is either red or blue. I am confused why you multiply them in this instance.
â user9995331
Aug 9 at 23:17
Why do you need to account for the 'other' possibilities the chose function is implied? The ball is either red or blue. I am confused why you multiply them in this instance.
â user9995331
Aug 9 at 23:17
you need to choose three balls but you also want to choose at least 1 read thus every time you need to choose a red with blue balls possibilities are 1red and 2 blue balls , 2 red and 1 blue balls , 3 red balls
â Deepesh Meena
Aug 9 at 23:18
you need to choose three balls but you also want to choose at least 1 read thus every time you need to choose a red with blue balls possibilities are 1red and 2 blue balls , 2 red and 1 blue balls , 3 red balls
â Deepesh Meena
Aug 9 at 23:18
add a comment |Â
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Why someone wants to close this interesting topic? Explain please your step.
â Michael Rozenberg
Aug 10 at 9:37