Hello all,
I have come back to college after a # of years out of school,
I am struggling with a few concepts in my discrete math class and some further help would be greatly appreciated as I have exhausted all other tutoring avenues.
Question:
How many permutations of the letters ABCDEFG contain:
a) The String BCD?
At first I didnt understand that the order of BCD mattered, for example CDB does not count. So I went about solving this the total wrong way,
Question 1) what part of this problem is clarifying that rule? I feel like it could go either way and is almost up for interpretation .
Question 2)
So i eventually figured out that since order matters you group BCD as 1 item
so its
BCD X A X E X F X G
which is
5!
what I dont understand is exactly the distribution of how this is playing out.
For example,
I would think
BCD X A = ABCD or ABCD (2!)
then
BCD X A X E = AEBCD, ABCDE, EABCD, EBCDA, BCDAE, BCDEA which is (3!)
makes sense, but what about:
EBCD, BCDE
what is handeling this portion of the options?
Thanks for your help and time.
I have come back to college after a # of years out of school,
I am struggling with a few concepts in my discrete math class and some further help would be greatly appreciated as I have exhausted all other tutoring avenues.
Question:
How many permutations of the letters ABCDEFG contain:
a) The String BCD?
At first I didnt understand that the order of BCD mattered, for example CDB does not count. So I went about solving this the total wrong way,
Question 1) what part of this problem is clarifying that rule? I feel like it could go either way and is almost up for interpretation .
Question 2)
So i eventually figured out that since order matters you group BCD as 1 item
so its
BCD X A X E X F X G
which is
5!
what I dont understand is exactly the distribution of how this is playing out.
For example,
I would think
BCD X A = ABCD or ABCD (2!)
then
BCD X A X E = AEBCD, ABCDE, EABCD, EBCDA, BCDAE, BCDEA which is (3!)
makes sense, but what about:
EBCD, BCDE
what is handeling this portion of the options?
Thanks for your help and time.