DS : Gmatprep

Question

Please explain

MA · Answer

totoal = 1000
nither = 880
either i or f = 120
f = 20
so only i = 120 -20 = 100

got C.

rbcola · Answer

I get C as well. But I get zero as the answer with the matrix method.

Basically 20 have fever so 880 do not. Of the 880, 880 have no inflamation so the intersection of inflamation and no fever is zero.

rnachloo · Answer

E.

Fever -> F, Inflammation -> I, Total -> T, Neither -> N

F + I - F (intersection) I + N = T

20 + I - F (intersection) I + 880 = 1000

Cannot find only F, as only F -> F - F (intersection) I

haas_mba07 · Answer

Creating a grid for the problem should make this easier.

Let x be the variable to find.

S1: 880 children had no inflammation and no fever.

This is not sufficient to determine Inflammation and No fever count. Not sufficient.

S2: No Inflammation and Fever = 20

Again not sufficient. 

S1 & S2: 20+ 880+x = 1000 
Sufficient.

Therefore C.

rnachloo · Answer

Are you sure hass_mba07. The second statement doesn't say "fever no inflamation". It just says 20 people have fever. (Of which who knows there could be any number of people with both fever and inflamation

haas_mba07 · Answer

I didn't use the "fever & no inflammation" row of my grid. Used the bottom total for "fever" which is either with inflammation and without inflammation .

If you read the rows as Inflammation/No Inflammation and the columns as "fever/no fever" and the end of the row and columns as total (on the right of rows and bottom of the columns) you should have 1000 as the total.

sgrover · Answer

You are assuming that there are no cases wiith both inflammation and fever .. The question doesnt say that there are no cases with both, but it doesnt deny either.. So, shd we not consider cases with both inflammation and fever.

sgrover · Answer

My mistake.. Fever cases include the common cases as well.. somehow got confused.

MA · Answer

good question............

if there are any cases of inflamation and fever, that is only possible with 20 people who have fever. 

lets suppose 15 people who have fever also have inflamation. then still we have the same number of people (100) with inflamation cuz it doesnot affect the people with only inflamation.

since we have information about the people who have fever, it is sufficient to know the number of people with iflamation only.

jamesrwrightiii · Answer

It's C
No math needed
880 were symptom free
They either had fever or inflammation, but not both
100 developed inflammation..

Although I do think the question could have been worded better ,but thay may have tipped people off...

jaynayak · Answer

Good Question and a nice trap.

We are so used to looking at traps that sometimes miss the obvious.

We have 1000 people, 880 without Immflamation or fever and 20 with fever.
Rest is 100.
Now these 100 surely donot have any fever as the number of people with fever is mentioned. And they surely are suffering from immflamation as the number of people not having any is also mentioned.
So the only choice left is Immflamation

amit79 · Answer

1)this is not ggod enough
2) again here we have 20 having fever
so if take both the options then

total=1000
neither Fever not Inflammation = 880 i.e. either F or I =(1000 - 880)=120
now, F=20 
hence only I=120-20=100

so ans should be C

DS : Gmatprep

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards