BTGmoderatorDC wrote:When 1,000 children were inoculated with a certain vaccine, some developed inflammation at the site of the inoculation and some developed fever. How many of the children developed inflammation but not fever ?

(1) 880 children developed neither inflammation nor fever
(2) 20 children developed fever.

OA C

Source: GMAT Prep

Let's take each statement one by one.

Say,

I = Number of children that developed inflammation but not fever;
F = Number of children that developed fever but not inflammation;
B = Number of children that developed both fever and inflammation
N = Number of children that developed neither fever nor inflammation

Thus, 1000 = I + B + F + N

We have to get the value of I.

(1) 880 children developed neither inflammation nor fever.

N = 880. But we can't get the value of I. Insufficient.

(2) 20 children developed fever.

B + F = 20. But we can't get the value of I. Insufficient.

(1) and (2) together

1000 = 880 + I + 20

I = 100. Sufficient.

The correct answer: C

Hope this helps!

-Jay
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