Data Sufficiency

Hi All,

We're asked - in a survey of retailers, what percent had purchased computers for business purposes. This question can be solved with a bit of logic (and no real math is needed).

1) 85 percent of the retailers surveyed who OWNED THEIR OWN STORE had purchased computers for business purposes.

Fact 1 introduces the idea that there are at two types of retails - those who own their own store and those who don't. The information in Fact 1 only gives us information on one of the two groups - and does not tell us anything about the number of of retailers in each group.
Fact 1 is INSUFFICIENT

2) 40 percent of the retailers surveyed owned their own store.

Fact 2 also introduces the idea that there are at two types of retails - those who own their own store and those who don't. The information in Fact 2 only gives us information on the percent of retailers who own their own store, but tells us nothing about whether those owners purchased computers for business purposes or not.
Fact 2 is INSUFFICIENT

Combined, we know:
40 percent of the retailers surveyed owned their own store.
85 percent of the retailers surveyed who OWNED THEIR OWN STORE had purchased computers for business purposes.

With this information, we still don't know anything about retailers who do NOT own their own stories, so there's no way to answer the given question.
Combined, INSUFFICIENT

Final Answer: E

GMAT assassins aren't born, they're made,
Rich

I thought I'd point out that Ceilidh's Double Matrix approach can be used for most questions featuring a population in which each member has two characteristics associated with it.
Here, we have a population of students, and the two characteristics are:
- owns store or doesn't own store
- purchased computers or did not purchase computers

This question type is VERY COMMON on the GMAT, so be sure to master the technique.

To learn more about the Double Matrix Method, watch this video: https://www.gmatprepnow.com/module/gmat- ... ems?id=919

Once you're familiar with this technique, you can attempt these additional practice questions:

Easy Problem Solving questions
- https://www.beatthegmat.com/finance-maj ... 67425.html

Medium Problem Solving questions
- https://www.gmatprepnow.com/module/gmat- ... /video/920
- https://www.beatthegmat.com/posted-spee ... 72374.html
- https://www.beatthegmat.com/motel-t271938.html
- https://www.beatthegmat.com/of-the-appl ... 70255.html
- https://www.beatthegmat.com/opening-nig ... 64869.html
- https://www.beatthegmat.com/at-least-10 ... 74669.html
- https://www.beatthegmat.com/prblem-solving-t279424.html

Difficult Problem Solving questions
- https://www.gmatprepnow.com/module/gmat- ... /video/946
- https://www.beatthegmat.com/ratio-problem-t268339.html
- https://www.beatthegmat.com/overlapping ... 65223.html
- https://www.beatthegmat.com/fractions-t264254.html
- https://www.beatthegmat.com/overlapping ... 64092.html
- https://www.beatthegmat.com/mba/2011/05 ... question-2

Easy Data Sufficiency questions
- https://www.gmatprepnow.com/module/gmat- ... /video/943
- https://www.beatthegmat.com/for-what-pe ... 70596.html
- https://www.beatthegmat.com/ds-quest-t187706.html

Medium Data Sufficiency questions
- https://www.beatthegmat.com/sets-matrix-ds-t271914.html
- https://www.beatthegmat.com/each-of-peo ... 71375.html
- https://www.beatthegmat.com/a-manufacturer-t270331.html
- https://www.beatthegmat.com/in-costume- ... 69355.html
- https://www.beatthegmat.com/mba/2011/05 ... question-1

Difficult Data Sufficiency questions
- https://youtu.be/dsCeqF9Kbk8
- https://www.beatthegmat.com/double-set- ... 71423.html
- https://youtu.be/dOZ9KM1m5Hs
- https://www.beatthegmat.com/sets-t269449.html
- https://www.beatthegmat.com/mba/2011/05 ... question-3

Cheers,
Brent

ben wade wrote:Q. In a survey of retailers, what percent had purchased computers for business purposes?
(1) 85 percent of the retailers surveyed who owned their own store had purchased computers for business purposes.
(2) 40 percent of the retailers surveyed owned their own store.

Statement One Alone:

85 percent of the retailers surveyed who owned their own store had purchased computers for business purposes.

Since we don't know the number of retailers who don't own their own stores and the percentage of those retailers who purchased computers for business purposes, statement one is not sufficient to answer the question.

Statement Two Alone:

40 percent of the retailers surveyed owned their own store.

Since statement two tells us nothing regarding the retailers who purchased their computer for business purposes, statement two alone does not answer the question.

Statements One and Two Together:

With both statements, although we know the percentage of the retailers who don't own their stores, we still don't know the percentage of those retailers who purchased computers for business purposes. The two statements together are not sufficient to answer the question.

Answer: E