# Thread: Permutation Question

1. ## Permutation Question

Q: How many strings with seven or more characters can be formed from the letters in EVERGREEN?

What am I suppose to do for this question? Since it asks for "seven or more", am i suppose to add up all the different possibilities?

My answerim not sure if its right)
[ (7!/(2!2!)) + (7!/(4!)) + (7!/(3!)) ]- For this i took out 2 E's, then 2 R's, then E and R
+
[ (8!/(3!2!)) + (8!/(4!)) ]- For this i took out 1 E, then 1 R.
+
[ 9!/(4!2!)

Is that the correct answer? If not please correct me.

Thanks
Creative

2. Originally Posted by Creative
Q: How many strings with seven or more characters can be formed from the letters in EVERGREEN?

What am I suppose to do for this question? Since it asks for "seven or more", am i suppose to add up all the different possibilities?

My answerim not sure if its right)
[ (7!/(2!2!)) + (7!/(4!)) + (7!/(3!)) ]- For this i took out 2 E's, then 2 R's, then E and R
+
[ (8!/(3!2!)) + (8!/(4!)) ]- For this i took out 1 E, then 1 R.
+
[ 9!/(4!2!)

Is that the correct answer? If not please correct me.

Thanks
Creative

3. Thanks, but that did not help.

4. Originally Posted by Creative
Thanks, but that did not help.
What about the formula about half way down that is relevant to your problem ....?

5. This is not a hard problem but it is very time consuming.
Just to find the number of seven strings there are many cases.
[EEEERRN]; [EEEERRG]; [EEEERRV]; [EEEERGN]; [EEEERVN];
[EEEERVG]; [EEEEVGN]; [EEERVGN]; [EERRVGN].
Now count each of those cases (If I have not missed some!)

Do the same thing for an eight string.

The nine string is the easy case (why?)