GMAT Math

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!

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

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

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]

No clue! Would appreciate it if someone can help on this, I have my exam tomorrow morning...Seems all the experts are on vacation;)

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

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.