White and black blocks are stacked in a vertical column so : DS Archive
Check GMAT Club App Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 08 Dec 2016, 06:44

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# White and black blocks are stacked in a vertical column so

Author Message
Director
Joined: 15 Aug 2005
Posts: 798
Location: Singapore
Followers: 2

Kudos [?]: 51 [0], given: 0

White and black blocks are stacked in a vertical column so [#permalink]

### Show Tags

23 Oct 2005, 18:07
00:00

Difficulty:

(N/A)

Question Stats:

100% (01:44) correct 0% (00:00) wrong based on 2 sessions

### HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

White and black blocks are stacked in a vertical column so that no two blocks of the same color are adjacent. IF there are 247 blocks in the stack, how many white blocks are there in the stack?

A. The top block in the stack is white
B. There are 5 white blocks in the 10 blocks at the bottom of the stack.
_________________

Cheers, Rahul.

Manager
Joined: 14 Apr 2003
Posts: 84
Followers: 1

Kudos [?]: 20 [0], given: 0

### Show Tags

23 Oct 2005, 18:12
rahulraao wrote:
White and black blocks are stacked in a vertical column so that no two blocks of the same color are adjacent. IF there are 247 blocks in the stack, how many white blocks are there in the stack?

A. The top block in the stack is white
B. There are 5 white blocks in the 10 blocks at the bottom of the stack.

Is OA A?

1) Would give us the whole stack's combination?
2) This cant tell us what is the lowest block?
SVP
Joined: 05 Apr 2005
Posts: 1731
Followers: 5

Kudos [?]: 72 [0], given: 0

### Show Tags

23 Oct 2005, 18:16
A. stat i is enough and ii isnot.
VP
Joined: 22 Aug 2005
Posts: 1120
Location: CA
Followers: 1

Kudos [?]: 100 [0], given: 0

### Show Tags

24 Oct 2005, 08:22
A.

as total number of blocks is odd, topmost and bottommost clock is of same color.

(1) total number of White blocks = (int) 247 / 2 + 1 = 124

(2) cannot determine sufficiently the bottommost block
Intern
Joined: 05 May 2005
Posts: 44
Followers: 1

Kudos [?]: 0 [0], given: 0

### Show Tags

24 Oct 2005, 08:44
We need to find which block is first or last since doing so will tell us which block color has 1 more than the other.

I) sufficient as we know white has the extra block
II) white could be first or black could be first which will give different totals so insufficient

Display posts from previous: Sort by