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data Sufficiency

by Tagne » Sun Mar 20, 2011 12:27 am
1. Is x + y < 1
a. X < 8/9
b. Y < 1/8

2. Is x + y < 1
a. X < 8/9
b. Y < 1/8

3. If m and n are integers, is m odd?
a. n + m is odd
b. n + m = n^2 + 5

4. if -2x > 3y, is x negative?
a. Y > 0
b. 2x + 5y -20 = 0

5. A manufacturer produced x percent more video cameras in 1994 than in 1993 and y percent more video cameras in 1995 than in 1994. If the manufacturer produced 1,000 cameras in 1993, how many video cameras did the manufacturer produce in 1995?
a. Xy = 20
b. X + y + xy/100 = 9.2

6. If X is not equal to -y, is x - y / (x + y) > 1?
a. X > 0
b. Y < 0
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by srcc25anu » Sun Mar 20, 2011 1:41 am
Q3. Is m odd???

stat 1: n+m = odd so one is even and one should be odd as odd + even = odd but no data on whether m is odd or n is odd
hence not sufficient

stat 2: n+m = n^2 +5
n^2 can e even or odd. if n^2 = even, n^2 + 5 = odd
and if n^2 = odd, n^2 + 5 = even
hence Not sufficient

together, n+m odd that is n^2+5 must be odd and n^2 must be even. so n must be even hence m is ODD
hence C
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by srcc25anu » Sun Mar 20, 2011 1:47 am
A manufacturer produced x percent more video cameras in 1994 than in 1993 and y percent more video cameras in 1995 than in 1994. If the manufacturer produced 1,000 cameras in 1993, how many video cameras did the manufacturer produce in 1995?
a. Xy = 20
b. X + y + xy/100 = 9.2

let video cameras (VC) produced in 1993 be 1
let video cameras (VC) produced in 1994 be (1+y/100)
let video cameras (VC) produced in 1993 be (1+x/100) * (1+y/100) = 1+1/100 [x+y+xy/100] - we need to find this

stat 2 alone is sufficient
hence B
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by srcc25anu » Sun Mar 20, 2011 2:05 am
6. If X is not equal to -y, is x - y / (x + y) > 1?
a. X > 0
b. Y < 0

stat 1: x>0, no information about y hence Not sufficient
if x = 2, y = -3 then x-y / (x+y) = -5 which is less than 1
if x = 2, y = -1 then x-y / (x+y) = 3 which is greater than 1

stat 2: y <0, no information about x hence insufficient
if y=-1, x=3 then then x-y / (x+y) = 2 which is greater than 1
if y=-1, x=-3 then then x-y / (x+y) = 1/2 which is less than 1

together still not sufficient
if x>0 (2) and y <0 (-1), then x-y / (x+y) = 2 (greater than 1)
if x>0 (2) and y <0 (-4), then x-y / (x+y) = -3 (less than 1)
hence E
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by Tagne » Sun Mar 20, 2011 10:16 am
The answer to question 3 is B. Please can anyone explain how that is?
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by kedar » Sun Mar 20, 2011 10:55 am
Yes answer to question 3 is B,

check whether m is odd or not?
a. n + m is odd
b. n + m = n^2 + 5

a. n+m=odd
possible values
0dd+even = odd
even+odd = odd

so m can be even or odd as we dont know what n is ?
so NOT SUFF

b. n+m = n^2 +5
=> m = n^2 -n + 5

Let say n is odd
m = odd^2 - odd + 5
m = Even+ 5 (odd^2 -odd = even 5^2-5=20)
m = even + odd = ODD

Let say n is even
m = even^2 - even + 5
m = even + 5 (even^2 -even = even)
m = even + odd = ODD

So SUFF

Hence the answer is B.
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by Tagne » Sun Mar 20, 2011 11:50 am
pls can anyone take a look at question 1?
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by chipmaker » Sun Mar 20, 2011 12:34 pm
Q1. Is x + y < 1

a. X < 8/9 -> Not sufficient
b. Y < 1/8 -> Not sufficient

a & b: X+Y < (8/9+1/8)
X+Y < 73/72

Hence not sufficient. Answer=E
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