GRE Prep 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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Each of the four children has a bag with five different colored discs
[#permalink]
18 Oct 2021, 05:29
18 Oct 2021, 05:29
1
Expert Reply
1
Bookmarks
00:00
Question Stats:
69% (02:14) correct
30% (02:08) wrong based on 13 sessions
Hide Show timer Statistics
Each of the four children has a bag with five different colored discs in it; red blue green yellow and orange. If each child in succession randomly chooses exactly one disc from his bag to flip into a hat. What is the probability that hat will no hold no repeated colours at the end flipping?
A- 1/5
B- 6/625
C- 24/625
D- 24/125
E- 6/125
A- 1/5
B- 6/625
C- 24/625
D- 24/125
E- 6/125
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: Each of the four children has a bag with five different colored discs
[#permalink]
18 Oct 2021, 06:01
18 Oct 2021, 06:01
1
Bookmarks
Carcass wrote:
Each of the four children has a bag with five different colored discs in it; red blue green yellow and orange. If each child in succession randomly chooses exactly one disc from his bag to flip into a hat. What is the probability that hat will no hold no repeated colours at the end flipping?
A- 1/5
B- 6/625
C- 24/625
D- 24/125
E- 6/125
A- 1/5
B- 6/625
C- 24/625
D- 24/125
E- 6/125
As with most probability questions on the GRE, we can use either counting techniques or probability rules.
Let's use probability rules:
P(no repeated colors) = P(ANY color disc is chosen 1st AND color of 2nd disc is different from 1st disc AND color of 3rd disc is different from 1st and 2nd disc AND color of 4th disc is different from other discs)
= P(ANY color disc is chosen 1st) x P(color of 2nd disc is different from 1st disc) x P(color of 3rd disc is different from 1st and 2nd disc) x P(color of 4th disc is different from other discs)
= 1 x 4/5 x 3/5 x 2/5
= 24/125
Answer: D
Re: Each of the four children has a bag with five different colored discs
[#permalink]
07 Nov 2022, 01:59
07 Nov 2022, 01:59
we can also calculate total results that are possible by counting, 5*5*5*5 = 625, then we need to fill 4 places with different disks say _ _ _ _. For first place we have 5 choices, then we can have any disk at the second place except the one we chose for 1st places this leaves us with 4 choices. This goes on until our all blanks are filled such that 5*4*3*2 = 120.
Now simplify 120/625 = 24/125
Now simplify 120/625 = 24/125
