Number of people who did not respond favorable for M = 20+40 = 60
Number of people who did not respond favorable for N = 35+35 = 70

(1) The number of voters who did not respond favorable for either candidate was 40.
Total Number of candiadtes who did not respond favorable =
Number of people who did not respond favorable for M +
Number of people who did not respond favorable for N -
Number of people who did not respond favorable for Both

= 60+70-40 = 90.

Therefore number of people who did not respond favorable for both = 90.
Therefore people who respnded favorable = 100-90 = 10.

(2) The number of voters who responded unfavorable for both candidates was 10.
From this we will know only unfavorable responses. But not NOTSUREresponses.
hence INSUFF

to calculate:
Total unfavorable = unfavourable for M + unfavourable for N + unfavourable for both
= 20+35 - 10 = 45.
Now we do not know NOT SURE respondents count.
Hence INSUFF.

pick A.

I myself came up with an wrong answer.Thanks kvcpk for your easy-to-understand answer.

limestone wrote:I myself came up with an wrong answer.Thanks kvcpk for your easy-to-understand answer.

Thanks Buddy. Glad it helped!!

gmatmachoman wrote:Favorable Unfavorable Not Sure
Candidate M 40 20 40
Candidate N 30 35 35

The table above shows the results of a survey of 100 voters each responded "favorable" or "unfavorable" or "not sure" when asked about their impressions of candidate M and of candidate N.

What was the number of voters who responded "favorable" for both candidates?


(1) The number of voters who did not respond "favorable" for either candidate was 40.

(2) The number of voters who responded "unfavorable" for both candidates was 10.

We can also solve it using a triple-axis matrix:

_____________M Fav______M UnFav_______M Not Sure____Total
N Fav__________x___________________________________30
N UnFav____________________________________________35
N Not Sure__________________________________________35
Total__________40_________20_____________40________100

What is x?

(1)
_____________M Fav______M UnFav_______M Not Sure____Total
N Fav__________x___________________________________30
N UnFav_______b1__________a1____________a2_________35
N Not Sure_____b2__________a3____________a4_________35
Total__________40_________20_____________40________100

I am not able to create a box here, so i will take help of the variables.
given that a1 + a2 + a3 + a4 = 40

Therefore, b1 + b2 = 35+35 - 40 =30
so, x = 40-30 = 10
SUFFICIENT

(2)

_____________M Fav______M UnFav_______M Not Sure____Total
N Fav__________x___________________________________30
N UnFav__________________10________________________35
N Not Sure__________________________________________35
Total__________40_________20_____________40________100

Cant solve for x. INSUFFICIENT.

CORRECT ANSWER (A)