FRACTIONS

[taneja.niks]

In a nationwide poll, N people were interviewed. If 1/4 of them answered "yes" to question 1, and of those, 1/3 answered "yes" to question 2, which of the following expressions represents the number of people interviewed who did not answer "yes" to both
questions?

(A) N/7

(B) 6N/7

(C) 5N/12

(D) 7N/12

(E) 11N/12


OA: D
PLEASE EXPLAIN

[diebeatsthegmat]

In a nationwide poll, N people were interviewed. If 1/4 of them answered "yes" to question 1, and of those, 1/3 answered "yes" to question 2, which of the following expressions represents the number of people interviewed who did not answer "yes" to both
questions?

(A) N/7

(B) 6N/7

(C) 5N/12

(D) 7N/12

(E) 11N/12


OA: D
PLEASE EXPLAIN

ummm i will solve the PS this following way
N/4 -> yes (1) => 3N/4 No (1)
n/4*1/3=N/12 yes (2) so N/4-N/12=1N/6 no (2)
the number both answer no is 3N/4-1N/6=7N/12

[clock60]

dear taneja
can you please verify OA!!!
sometimes it is misleading

[taneja.niks]

sorry the answer is E

[goyalsau]

sorry the answer is E

Ya answer should be E.

[diebeatsthegmat]

In a nationwide poll, N people were interviewed. If 1/4 of them answered "yes" to question 1, and of those, 1/3 answered "yes" to question 2, which of the following expressions represents the number of people interviewed who did not answer "yes" to both
questions?

(A) N/7

(B) 6N/7

(C) 5N/12

(D) 7N/12

(E) 11N/12


OA: D
PLEASE EXPLAIN

ummm i will solve the PS this following way
N/4 -> yes (1) => 3N/4 No (1)
n/4*1/3=N/12 yes (2) so N/4-N/12=1N/6 no (2)
the number both answer no is 3N/4-1N/6=7N/12

oh yeah, dunno what i was thinking at 3 am lol....
N/12 people who answered both yes thus to find the people answered both no it shud be N-N/12=E
h i cant sleep!

[saurabhmahajan]

sorry ... but i still not understood.
please help me with the explanation.

[fsutanto]

Saurabh, I would answer it this way...

# of people who answered NO to question 1:
(3/4)N

# of people who answered YES to question 1 AND NO to question 2:
(1/4)N * (1 - 1/3) = (1/4)N * (2/3) = (2/12)N

Summing both the above leads to:
(3/4)N + (2/12)N = (9/12)N + (2/12)N = (11/12)N

So the number of people interviewed who did not answer to BOTH questions is (11/12)N, which is (E).

Trust this explains your question.

[limestone]

To find the No. of people did not answer yes to both question, just find the no. of them that did say yes to both question, then subtract the total no. of people to the no. of who said yes to both.

No. of people said yes to 1st question: 1/4N
Of those said yes to 1st, 1/3 said yes to the second, hence no. of people said yes to both : 1/4N* 1/3 = 1/12*N

Thus no. of people did not say yes to both questions: 1N- 1/12*N = 11/12*N
Pick E.