BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

sets

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 99
Joined: Fri Jul 13, 2012 1:35 am
Thanked: 1 times
Followed by:1 members

sets

by AJWILL » Sat Aug 04, 2012 12:40 pm
In a certain locality, 25% of the residents read newspaper A and 20 percent of the residents read newspaper B. What percent of the residents in that locality read neither newspaper A nor newspaper B?
(1) 4/5 of the residents who read newspaper A also read newspaper B.
(2) Total number of residents in locality are more than 500.
Top
Source: — Data Sufficiency |
User avatar
Legendary Member
Posts: 520
Joined: Sat Apr 28, 2012 9:12 pm
Thanked: 339 times
Followed by:49 members
GMAT Score:770

by eagleeye » Sat Aug 04, 2012 1:00 pm
AJWILL wrote:In a certain locality, 25% of the residents read newspaper A and 20 percent of the residents read newspaper B. What percent of the residents in that locality read neither newspaper A nor newspaper B?
(1) 4/5 of the residents who read newspaper A also read newspaper B.
(2) Total number of residents in locality are more than 500.
We know that total number = 100
Now we are given that 25 read A and 20 read B.
We need to find the ones who don't read A or B. Lets call them as totaling N.
Let's call people who read both common readers as totaling C.

Now using set theory/venn diagrams, we know that
Total = A + B - C + N
100 = 25 + 20 -C + N
So if we know either of C or N, we have sufficiency.

With that in mind, let's look at the options:

(1) 4/5 of the residents who read newspaper A also read newspaper B.
We are told that C = 4/5*A = 4/5*25 = 20. Hence we can find N using the equation above. Sufficient.

(2) Total number of residents in locality are more than 500.
Who cares about the total number. We are interested in percentages. Insufficient.

A is correct. :)
Top
Post new topic Post Reply
• Page 1 of 1