kept on a stool

Expert replies

sanju09: GMAT Instructor; Posts: 3650; Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members; Location: India; Thanked: 267 times; GMAT Score:760

by sanju09 » Thu May 06, 2010 6:16 am

The length of a ladder is exactly equal to the height of the wall it is resting against. If lower end of the ladder is kept on a stool of height 3 and the stool is kept 9 away from the wall, the upper end of the ladder coincides with the top of the wall. What is the height of the wall?
(A) 11
(B) 12
(C) 15
(D) 18
(E) 21

The mind is everything. What you think you become. -Lord Buddha

Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com

Like this post

Source: Beat The GMAT — Problem Solving | Thu May 06, 2010 6:16 am

liferocks: Legendary Member; Posts: 576; Joined: Sat Mar 13, 2010 8:31 pmFollowed by: 1 member; Thanked: 97 times

by liferocks » Thu May 06, 2010 6:30 am

ladder wall and distance of the stool from wall makes an right angled triangle where one side is 9

if its a 3,4,5 triangle then other sides will be 12 and 15

if the side of wall is 12 then total height of wall..include the stool height=length of ladder=15

Ans option C 15

"If you don't know where you are going, any road will get you there."
Lewis Carroll

Like this post

Ashish8: Senior | Next Rank: 100 Posts; Posts: 52; Joined: Sat Jan 23, 2010 9:08 pm; Thanked: 2 times

by Ashish8 » Thu May 06, 2010 7:26 am

Can someone verify if this method works. I got the same answer as liferocks, albeit it was negative.

The ladder is leaning on the wall and the floor and the wall make a right angle.

height of slanted ladder = a
Wall height = a + 3

pythagorean theorem:

9^2 + (a + 3)^2 = a^2 (FOIL)

81 + a^2 + 6a + 9 = a^2 (Subtract a^2)

81 + 6a + 9 = 0 (Subtract 90)

6a = -90

a = -15

Like this post

liferocks: Legendary Member; Posts: 576; Joined: Sat Mar 13, 2010 8:31 pmFollowed by: 1 member; Thanked: 97 times

by liferocks » Thu May 06, 2010 7:40 am

Ashish8 wrote:Can someone verify if this method works. I got the same answer as liferocks, albeit it was negative.

The ladder is leaning on the wall and the floor and the wall make a right angle.

height of slanted ladder = a
Wall height = a + 3

pythagorean theorem:

9^2 + (a + 3)^2 = a^2 (FOIL)

81 + a^2 + 6a + 9 = a^2 (Subtract a^2)

81 + 6a + 9 = 0 (Subtract 90)

6a = -90

a = -15

just a small correction
wall height is a and from pythagororus theorem we get

9^2+(a-3)^2=a^2

"If you don't know where you are going, any road will get you there."
Lewis Carroll

Like this post

kstv: Legendary Member; Posts: 610; Joined: Fri Jan 15, 2010 12:33 amFollowed by: 2 members; Thanked: 47 times

by kstv » Thu May 06, 2010 8:11 am

hÂ² = 9Â² + (h-3)Â²
6h = 90
h = 15

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

559 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review