GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 17 Jan 2020, 11:11

### 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

# In a stack of boards at a lumber yard, the 20th board counting from th

Author Message
TAGS:

### Hide Tags

Manager
Joined: 22 Sep 2005
Posts: 207
In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

Updated on: 23 Jul 2019, 01:35
9
67
00:00

Difficulty:

35% (medium)

Question Stats:

61% (01:04) correct 39% (01:04) wrong based on 1019 sessions

### HideShow timer Statistics

In a stack of boards at a lumber yard, the 20th board counting from the top of the stack is immediately below the 16th board counting from the bottom of the stack. How many boards are in the stack?

A. 38
B. 36
C. 35
D. 34
E. 32

Originally posted by netcaesar on 14 Nov 2006, 13:59.
Last edited by Bunuel on 23 Jul 2019, 01:35, edited 3 times in total.
Renamed the topic and edited the question.
Math Expert
Joined: 02 Sep 2009
Posts: 60460
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

03 Sep 2012, 05:18
17
15
vidhya16 wrote:
Guys,

Im confused with the phrase "immediately below 16 from the bottom". When you count something and you say immediately below something doesnt that it mean next number in the counting. In this example it will be 17th. How do you guys say it is 15th from the bottom?

Any clarification will help on Tuesday attempt.

Thanks

In a stack of boards at a lumber yard, the 20th board counting from the top of the stack is immediately below the 16th board counting from the bottom of the stack. How many boards are in the stack?

A. 38
B. 36
C. 35
D. 34
E. 32

There are some number of boards stacked.

20th board from the top is immediately below the 16th board from the bottom:

1
2
3
.
.
.
16
20 15
14
13
.
.
.
3
2
1

As you can see 20th board from the top is immediately below the 16th board from the bottom. The total number of boards 20(red)+14(blue)=34.

_________________
Manager
Joined: 08 Jun 2006
Posts: 239
Location: Washington DC
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

14 Nov 2006, 14:32
4
3
20th board from top is 15th (immediately below the 16th board) from bottom. Therefore, there are 14 more boards below the 20th board (from top).
Total number of boards = 34
##### General Discussion
Intern
Joined: 08 Jan 2012
Posts: 6
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

02 Sep 2012, 08:17
Guys,

Im confused with the phrase "immediately below 16 from the bottom". When you count something and you say immediately below something doesnt that it mean next number in the counting. In this example it will be 17th. How do you guys say it is 15th from the bottom?

Any clarification will help on Tuesday attempt.

Thanks
Manager
Joined: 25 Apr 2013
Posts: 56
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

19 Feb 2015, 09:02
2
1
We can actually quickly try it out with lesser number of planks.

Say 4th from the top is immediately below 3rd from the bottom.

-------------
-------------
-------------
-------------
-------------

Total number of planks = 4+3-2 = 5

This in fact would be the case with any plank. For example, 3rd from the top is below 4th from the bottom.

Total number of planks = 3+4-2 = 5

Here, 20th from the top is below 16th from the bottom
-> Total number of planks = 20+16-2 = 34
SVP
Joined: 06 Nov 2014
Posts: 1868
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

18 Oct 2015, 12:18
novice12 wrote:
In a Stack of boards at a lumber yard, the 20th board counting from the top of the stack is immediately below the 16th board counting from the bottom of the stack. How many boards are in the stack?
a. 38
b. 36
c. 35
d. 34
e. 32

We need the 20th board, when we start counting from the top.
This board is immediately below the 16th board from the bottom. i.e. This is the 15th board from the bottom
Hence we have 14 more boards below this.

Total number of boards = 14(No. of boards below the one in consideration) + 20(No. of boards above the one in consideration) = 34 Option D
Senior SC Moderator
Joined: 22 May 2016
Posts: 3734
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

05 Jul 2017, 15:42
2
1
Baten80 wrote:
In a stack of boards at a lumber yard, the 20th board counting from the top of the stack is immediately below the 16th board counting from the bottom of the stack. how many boards are in the stack?

A) 38

B) 36

C) 35

D) 34

E) 32
Attachment:

stack of boards.jpg [ 797.06 KiB | Viewed 9417 times ]

After 20 seconds of trying to do the math in my head, I sketched quickly and it got a lot easier.

I've attached a diagram.

Though there are two columns, they represent one stack.

If you were standing in front of this one stack to count boards, for the left column, you would put your finger on the top board and count downward. The right column is the same stack, only this time you have reached down and started counting from the bottom upwards. I slid the two apart to figure out where GREEN and YELLOW fell in relation to boards above and below, and to get arithmetic correct.

Call the board that is 20th counting down from the top GREEN.

That GREEN board sits one below the board that is 16th counting up from the bottom. Call that 16th-from-bottom YELLOW.

GREEN has 19 boards above it. YELLOW has 15 boards below it.

But there is overlap: GREEN takes the ordinal "counting place" of 15th board from bottom (crossed out in diagram to indicate it shouldn't be counted), and

YELLOW takes the ordinal counting place of 19th board from top counting down (also crossed out).

Don't think about the blacked out parts. In ordinal (nth) terms, they don't match, and they'll confuse, which is precisely the point of this question.

So we have 18 + 1 + 1 + 14 = 34.

Hope it helps.

_________________
SC Butler has resumed! Get two SC questions to practice, whose links you can find by date, here.

Never doubt that a small group of thoughtful, committed citizens can change the world; indeed, it's the only thing that ever has -- Margaret Mead
GMAT Club Legend
Joined: 12 Sep 2015
Posts: 4214
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

13 Jan 2018, 10:09
1
Top Contributor
netcaesar wrote:
In a stack of boards at a lumber yard, the 20th board counting from the top of the stack is immediately below the 16th board counting from the bottom of the stack. How many boards are in the stack?

A. 38
B. 36
C. 35
D. 34
E. 32

Let's start from the bottom and work our way up:

We'll start with the 16th board counting from the bottom of the stack

Right BELOW that 16th board, we have a board that we'll call Larry.
So, Larry is the 15th board counting from the bottom of the stack.
So, starting from the bottom and working our way up to Larry, we have 15 boards so far.

Larry is the 20th board counting from the TOP of the stack
In other words, there are 19 boards ABOVE Larry.
So, including those 19 boards, we now have 34 boards in TOTAL.

Cheers,
Brent
_________________
Test confidently with gmatprepnow.com
EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 15929
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

15 Mar 2018, 13:30
Hi All,

Since the answers to the question are all numbers, we can use the answers 'against' the prompt and TEST THE ANSWERS. Here's how…

IF the number of boards was 36, then the 20th board from the top would be the 17th board from bottom, which would be UNDER the 18th board from the bottom. This is NOT a match for what we were told. Elimate B. Now we know that the number of boards has to be SMALLER. Let's test D next.

IF the number of boards was 34, then the 20th board from the top would be the 15th board from the bottom, which would be UNDER the 16th board from the bottom. This IS a match for what we were told, so this MUST be the answer.

GMAT assassins aren't born, they're made,
Rich
_________________
Contact Rich at: Rich.C@empowergmat.com

The Course Used By GMAT Club Moderators To Earn 750+

souvik101990 Score: 760 Q50 V42 ★★★★★
ENGRTOMBA2018 Score: 750 Q49 V44 ★★★★★
Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 9032
Location: United States (CA)
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

30 Mar 2018, 10:59
2
netcaesar wrote:
In a stack of boards at a lumber yard, the 20th board counting from the top of the stack is immediately below the 16th board counting from the bottom of the stack. How many boards are in the stack?

A. 38
B. 36
C. 35
D. 34
E. 32

If the 20th board counting from the top of the stack is immediately below the 16th board counting from the bottom of the stack, then the 19th board counting from the top of the stack is exactly the 16th board counting from the bottom of the stack. In other words, there are 18 boards above the 16th board counting from the bottom of the stack. Thus, there are 18 + 16 = 34 boards in the stack.

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
181 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Manager
Joined: 24 Sep 2018
Posts: 135
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

07 Oct 2018, 22:40
vidhya16 wrote:
Guys,

Im confused with the phrase "immediately below 16 from the bottom". When you count something and you say immediately below something doesnt that it mean next number in the counting. In this example it will be 17th. How do you guys say it is 15th from the bottom?

Any clarification will help on Tuesday attempt.

Thanks

vidhya16,

Hey If this pictorial representation helps you.

Attachment:

IMG_2762.jpg [ 1.35 MiB | Viewed 19938 times ]
Manager
Joined: 09 Apr 2017
Posts: 79
GPA: 3.99
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

04 Dec 2018, 10:40
1
Posted from my mobile device
Attachments

E68D1F8A-38CD-40E5-9716-A83F53D26438.jpeg [ 512.63 KiB | Viewed 17364 times ]

Senior Manager
Joined: 05 Mar 2017
Posts: 259
Location: India
Concentration: General Management, Marketing
GPA: 3.6
WE: Marketing (Hospitality and Tourism)
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

07 Jul 2019, 07:53
We can actually quickly try it out with a lesser number of planks.

Say 4th from the top is immediately below 3rd from the bottom.

-------------
-------------
-------------
-------------
-------------

Total number of planks = 4+3-2 = 5

This, in fact, would be the case with any plank. For example, 3rd from the top is below 4th from the bottom.

Total number of planks = 3+4-2 = 5

Here, 20th from the top is below 16th from the bottom
-> Total number of planks = 20+16-2 = 34
Manager
Joined: 28 Jan 2019
Posts: 130
Location: Peru
GMAT 1: 640 Q49 V29
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

07 Jul 2019, 08:29
How many boards can be translated to: # of boards above 20th board + 20th board + # of boards below 20th board

# of boards above 20: 19

20th board: 1

# of boards below 20: Since it is below 16th board from the bottom of the stack, the 20th (from the top) would be the 15th from the bottom, so it has 14 boards below:14

1+14+19 = 34, (D) is the answer.
Non-Human User
Joined: 09 Sep 2013
Posts: 13964
Re: In a stack of boards at a lumber yard, the 20th board counting from th  [#permalink]

### Show Tags

23 Jul 2019, 01:31
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: In a stack of boards at a lumber yard, the 20th board counting from th   [#permalink] 23 Jul 2019, 01:31
Display posts from previous: Sort by