It is currently 19 Oct 2017, 22:55

### 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

# A 25-foot ladder is placed against a vertical wall of a building

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 41884

Kudos [?]: 128932 [0], given: 12183

A 25-foot ladder is placed against a vertical wall of a building [#permalink]

### Show Tags

01 Sep 2017, 07:48
00:00

Difficulty:

(N/A)

Question Stats:

88% (01:44) correct 13% (00:00) wrong based on 23 sessions

### HideShow timer Statistics

A 25-foot ladder is placed against a vertical wall of a building, with the bottom of the ladder standing on concrete 7 feet from from the base of the building. If the top of the ladder slips down 4 feet, then the bottom of the ladder will slide out

(A) 4 ft
(B) 5 ft
(C) 6 ft
(D) 7 ft
(E) 8 ft
[Reveal] Spoiler: OA

_________________

Kudos [?]: 128932 [0], given: 12183

Intern
Joined: 21 May 2017
Posts: 16

Kudos [?]: 4 [0], given: 3

Re: A 25-foot ladder is placed against a vertical wall of a building [#permalink]

### Show Tags

01 Sep 2017, 08:25
The ladder when inclined against the wall forms a right triangle - the ladder being the hypotenuse, the vertical wall and ground being the other 2 sides of the right triangle.

the base is given as 7 feet. Using this info we can calculate the vertical height by applying Pythagoras theorem. Therefore height is 24 feet (easier to find this if we know the 25-24-7 right triangle). If the ladder slips by 4 feet the height is now 20 feet and the ladder length is the same (25 feet). the new base can again be calculated by Pythagoras theorem or by simply applying the 3-4-5 multiple concept of right triangle.

thus we can calculate the new base as 15 feet.
Therefore the ladder has slipped by 8 feet (15-7).

Ans is E

Please guide if there is a faster way to solve this.

Kudos [?]: 4 [0], given: 3

Manager
Joined: 06 Jan 2015
Posts: 208

Kudos [?]: 98 [0], given: 448

Location: India
Concentration: Operations, Finance
GPA: 3.35
WE: Information Technology (Computer Software)
Re: A 25-foot ladder is placed against a vertical wall of a building [#permalink]

### Show Tags

01 Sep 2017, 08:30
Bunuel wrote:
A 25-foot ladder is placed against a vertical wall of a building, with the bottom of the ladder standing on concrete 7 feet from from the base of the building. If the top of the ladder slips down 4 feet, then the bottom of the ladder will slide out

(A) 4 ft
(B) 5 ft
(C) 6 ft
(D) 7 ft
(E) 8 ft

From Pythagoras

$$AC^2=AB^2+BC^2$$

625-49=576

AB=24

From another triangle

$$25^2= 20^2+(7+x)^2$$

$$625=400 + (7+x)^2$$

$$(7+x)^2= 225$$

x=8
Attachments

Solution.jpg [ 18.38 KiB | Viewed 441 times ]

_________________

आत्मनॊ मोक्षार्थम् जगद्धिताय च

Kudos [?]: 98 [0], given: 448

BSchool Forum Moderator
Joined: 26 Feb 2016
Posts: 1454

Kudos [?]: 594 [0], given: 16

Location: India
WE: Sales (Retail)
A 25-foot ladder is placed against a vertical wall of a building [#permalink]

### Show Tags

01 Sep 2017, 08:32
mahu101, No shorter method to solve it!

The ladder forms a right angled triangle with the wall.
The length of the ladder is the hypotenuse(25 feet)
Since the distance from the wall is 7 feet, the distance
from the base of the building can be calculated using the Pythagorean theorem.
Let this distance be x.
$$x^2 = 625 - 49 = 576$$
$$x = 24$$

Since the ladder is going down by 4 feet, the ladder is 20 feet from base of the building.
Let the distance from the wall be y.
Using the same property of the right triangle,
$$y^2 = 625 - 400 =225$$
$$y = 15$$

From 7 feet, the ladder moves a further 8 feet to move a total of 15 feet
Hence, the distance is 8 feet(Option E)
_________________

Stay hungry, Stay foolish

Kudos [?]: 594 [0], given: 16

Intern
Joined: 21 May 2017
Posts: 16

Kudos [?]: 4 [0], given: 3

Re: A 25-foot ladder is placed against a vertical wall of a building [#permalink]

### Show Tags

01 Sep 2017, 10:18
Thank you pushpitkc.

Kudos [?]: 4 [0], given: 3

Re: A 25-foot ladder is placed against a vertical wall of a building   [#permalink] 01 Sep 2017, 10:18
Display posts from previous: Sort by