If the two floors in a certain building are 9 feet apart, how many steps are there in a set of stairs that extends from

Expert replies

Previous Topic Next Topic

Gmat_mission: Legendary Member; Posts: 1622; Joined: Thu Mar 01, 2018 7:22 amFollowed by: 2 members

by Gmat_mission » Thu Sep 10, 2020 12:34 am

Timer

00:00

Answers

Stats

Difficulty—

If the two floors in a certain building are 9 feet apart, how many steps are there in a set of stairs that extends from the first floor to the second floor of the building?

(1) Each step is 3/4 foot high.
(2) Each step is 1 foot wide.

Answer: A

Source: Official Guide

Like this post

Source: Beat The GMAT — Data Sufficiency | Thu Sep 10, 2020 12:34 am

deloitte247: Legendary Member; Posts: 2214; Joined: Fri Mar 02, 2018 2:22 pmFollowed by: 5 members

Re: If the two floors in a certain building are 9 feet apart, how many steps are there in a set of stairs that extends f

by deloitte247 » Fri Sep 11, 2020 9:19 am

Given that =>2 floors are 9ft apart

Target question => How many steps are there in a set of stairs that extends from the first floor to the second floor

Length of a set of stairs from 1st to 2nd floor = 9ft

Statemnet 1 => Each step is 3/4 foot height
In other words, length of 1 step = 3/4 foot
total steps = 9ft
1 step = 3/4 foot
then x steps = 9ft
x = 9 / 3/4
x = 9 * 4/3 = 12 steps
Statement 1 is SUFFICIENT

Statement 2 => Each step is 1 foot wide
This making reference to the width occupied by 1 step and not the height occupied by 1 step out of the whole length of a set of stair which spans for 9ft. Hence, the number of stairs cannot be evaluated, statement 2 is not SUFFICIENT.

Since only statement 1 alone is SUFFICIENT,
Answer = A

Like this post

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

Re: If the two floors in a certain building are 9 feet apart, how many steps are there in a set of stairs that extends f

by Brent@GMATPrepNow » Sat Sep 12, 2020 6:34 am

Gmat_mission wrote: ↑
Thu Sep 10, 2020 12:34 am
If the two floors in a certain building are 9 feet apart, how many steps are there in a set of stairs that extends from the first floor to the second floor of the building?

(1) Each step is 3/4 foot high.
(2) Each step is 1 foot wide.

Answer: A

Source: Official Guide

First, we need to recognize that all target questions are IMPOSSIBLE to answer without any additional information. In other words, for any target question there will be more than one possible answer.

So, when you see the target question (in this case, it's How many steps are there in a set of stairs that extends from the first floor to the second floor of the building? ), we should STOP and ask ourselves, WHY is it impossible to answer this question?

In this case, we can't answer the question, because we don't know how "big" each stair is. If each stair is 4.5 feet high, then there will be only 2 stairs to fill in the 9 feet of height between floors. If each stair is 1 foot high, then there will be 9 stairs to fill in the 9 feet of height. If each stair is 3 feet high, then there will be 3 stairs. And so on.

Now that we understand WHY this target question is impossible to answer without any additional information, we should ask, What additional information will help me answer the target question? .

At this point, it's easy to see what we need. We need to know the height of each individual step.

Great. Now, we can start checking each statement.

Statement 1 tells us the height of each step. PERFECT. It must be sufficient. In fact, we need not even perform any calculations. For Data Sufficiency questions, we need only determine whether we have sufficient information to answer the target question. We already know that statement 1 provides sufficient information, so performing any calculations will be a waste of our precious time.

Statement 2 provides no information that will help me determine the height of each step. So, it is NOT sufficient.

Answer: A

For more tips and strategies for solving Data Sufficiency questions, see my comprehensive set of free videos at: https://www.gmatprepnow.com/module/gmat-data-sufficiency

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 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