Last visit was: 12 Dec 2024, 05:42 It is currently 12 Dec 2024, 05:42
Close
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Close
Request Expert Reply
Confirm Cancel
User avatar
TheBipedalHorse
Joined: 16 Jun 2021
Last visit: 12 Dec 2023
Posts: 109
Own Kudos:
Given Kudos: 98
Posts: 109
Kudos: 34
Kudos
Add Kudos
Bookmarks
Bookmark this Post
avatar
rprasad6310
Joined: 06 Jan 2022
Last visit: 17 Jul 2022
Posts: 31
Own Kudos:
Given Kudos: 9
Location: India
Posts: 31
Kudos: 7
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
TheBipedalHorse
Joined: 16 Jun 2021
Last visit: 12 Dec 2023
Posts: 109
Own Kudos:
Given Kudos: 98
Posts: 109
Kudos: 34
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
IanStewart
User avatar
GMAT Tutor
Joined: 24 Jun 2008
Last visit: 09 Dec 2024
Posts: 4,126
Own Kudos:
9,912
 [1]
Given Kudos: 97
 Q51  V47
Expert reply
Posts: 4,126
Kudos: 9,912
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
You could just imagine arranging the 8 people in a random order, and ask: what is the probability the CEO will come before the CTO, and the CTO before the COO? That probability is 1/6, because there are 6 orders the CEO, CTO and COO could end up speaking in, and each of those 6 orders is equally likely. So in 1/6 of all of the orders we could make, the CEO, CTO and COO will end up speaking in that order, and the answer is 8!/6.
User avatar
IanStewart
User avatar
GMAT Tutor
Joined: 24 Jun 2008
Last visit: 09 Dec 2024
Posts: 4,126
Own Kudos:
9,912
 [1]
Given Kudos: 97
 Q51  V47
Expert reply
Posts: 4,126
Kudos: 9,912
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
And that's the same answer as your friend got -- your friend might have thought of it this way: "we have 8 slots on the speaking schedule to fill, and we can choose three of them for the CEO, CTO and COO in 8C3 ways. Once we choose those slots the sequence is predetermined: the CEO goes in the first slot we choose, the CTO in the next, the COO in the last. Then there are 5 slots left to fill using the other five people, and we have 5 choices for the first, 4 for the next, and so on, and the answer is 8C3 * 5!." That also gives the answer.
User avatar
TheBipedalHorse
Joined: 16 Jun 2021
Last visit: 12 Dec 2023
Posts: 109
Own Kudos:
Given Kudos: 98
Posts: 109
Kudos: 34
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Ian, your answer makes sense! Thanks for sharing a new insight - combining probability and combinations to figure out the problem!
avatar
rprasad6310
Joined: 06 Jan 2022
Last visit: 17 Jul 2022
Posts: 31
Own Kudos:
Given Kudos: 9
Location: India
Posts: 31
Kudos: 7
Kudos
Add Kudos
Bookmarks
Bookmark this Post
8C3 * 5! is the correct answer..Thanks,,
Moderator:
Math Expert
97842 posts