Dear Stacey Koprince,
Many thanks for your ongoing help. I have two questions if you don't mind:
1)What's the difference between a and b below:
a. In how many different orders can the people Alice, Benjamin, Charlene, David, Elaine, Frederik, Gale, and Harold be standing on line if each of Alice, Benajmin, Charlene, must be on the line before each of Frederic, Gale and Harold?
b. In how many different ways can the letters A,A, B,B,B,C,D,E be arranged if the letter C must be to the right of letter D?
I did not really understand why we didnt use the 8! in the formula in a, but rather, we multiplied 28x2x6x6=2016 ways
2)In arcs and circles, when do I use the tip that the measure of an arc is twice the measure of its corresponding interior angle?
Thank you!
Combinations
This topic has expert replies
- sanju09
- GMAT Instructor
- Posts: 3650
- Joined: Wed Jan 21, 2009 4:27 am
- Location: India
- Thanked: 267 times
- Followed by:80 members
- GMAT Score:760
Thouraya wrote:Dear Stacey Koprince,
Many thanks for your ongoing help. I have two questions if you don't mind:
1)What's the difference between a and b below:
a. In how many different orders can the people Alice, Benjamin, Charlene, David, Elaine, Frederik, Gale, and Harold be standing on line if each of Alice, Benajmin, Charlene, must be on the line before each of Frederic, Gale and Harold?
b. In how many different ways can the letters A,A, B,B,B,C,D,E be arranged if the letter C must be to the right of letter D?
I did not really understand why we didnt use the 8! in the formula in a, but rather, we multiplied 28x2x6x6=2016 ways
2)In arcs and circles, when do I use the tip that the measure of an arc is twice the measure of its corresponding interior angle?
Thank you!
Dear Thouraya, kindly let's know if anybody other than Stacey Koprince may also answer this thread.
Regards
The mind is everything. What you think you become. -Lord Buddha
Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001
www.manyagroup.com
Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001
www.manyagroup.com
-
- Senior | Next Rank: 100 Posts
- Posts: 36
- Joined: Thu Dec 31, 2009 5:54 am
- Location: New York City
- Thanked: 2 times
I don't understand why you're multiplying 28x2x6x6 for 1a.
If you have A,B,C,D,E,F,G,H and ABC must be in front of FGH, then its:
The total number of ways to arrange ABCDE (5!) x total number of ways to arrange FGH (3! or 6) = 6!
PLUS
The total number of ways to arrange ABC (3! or 6) x total number of ways to arrange DEFGH (5!) = 6!
6! + 6! = 1440
Why isn't 1440 the answer?[/u]
If you have A,B,C,D,E,F,G,H and ABC must be in front of FGH, then its:
The total number of ways to arrange ABCDE (5!) x total number of ways to arrange FGH (3! or 6) = 6!
PLUS
The total number of ways to arrange ABC (3! or 6) x total number of ways to arrange DEFGH (5!) = 6!
6! + 6! = 1440
Why isn't 1440 the answer?[/u]
- sanju09
- GMAT Instructor
- Posts: 3650
- Joined: Wed Jan 21, 2009 4:27 am
- Location: India
- Thanked: 267 times
- Followed by:80 members
- GMAT Score:760
Sorry for attending it too late, you might have written your test by now. Loved your address mode but I am not the only Tiger, oops Mr. Titan around. I can see posts started pouring in, so we can afford to wait for more responses as your test is no more an emergency now.Thouraya wrote:Dear GMAT Titan,
You are more than welcome to answer the thread! Actually, I'd really be grateful!!
Try to be detailed Mr.Titan
Really appreciate your on-going help,
Best,
T
The mind is everything. What you think you become. -Lord Buddha
Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001
www.manyagroup.com
Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001
www.manyagroup.com