modulus ....its eating my brain !!

[pappueshwar]

hi all,
pls assist in solving the below DS problem

If n is not equal to 0, is |n| < 4 ?

(1) n^2 > 16

(2) 1 / |n| > n

[patanjali.purpose]

hi all,
pls assist in solving the below DS problem

If n is not equal to 0, is |n| < 4 ?

(1) n^2 > 16

(2) 1 / |n| > n

question implies IS -4<n<4?
(1) (n-4)(n+4) >0 ==> n>4; n<-4 ==> sufficient
(2) take n =-3; s2 is true and ans is YES; BUT take n=-8, s2 is true but ans is NO ==> Insufficient

IMO A

[[email protected]]

If n is not equal to 0, is |n| < 4 ?

(1) n^2 > 16

(2) 1 / |n| > n


Let me have the privilege of explaining this sum in detail...

Firstly we are asked -4 < n < 4


Statement 1: n^2 >16 It means n > 4 or n < -4

this states the exact opposite of what is asked... We are asked is n between -4 and 4 and we are given in statement 1 that n > 4 and n < -4 hence we know that n is not between 4 and -4.
Hence statement 1 is sufficient...


Statement 2: 1/|n| > n

Solve the inequality further...

1/|n| - n > 0

[1 - n |n|] > 0

This equation stands in 4 circumstances,

1] when n is between 0 and 1

2] when n is between 0 and -1

3] when n=0

4] when n < -1


For our statement to hold true, it should hold true in all the above 4 cases.

But unfortunately it does not in the 4 th case..

eg put the values in the equation [1 - n |n|]

let us say that n = -8

[1 - (-8) 8]

it gives us 65 which is greater than 0


but n is not between 4 and -4.

Hence our OA is A....



Hope this explanation really helped!!!

[pappueshwar]

hi all,
pls assist in solving the below DS problem

If n is not equal to 0, is |n| < 4 ?

(1) n^2 > 16

(2) 1 / |n| > n

question implies IS -4<n<4?
(1) (n-4)(n+4) >0 ==> n>4; n<-4 ==> sufficient
(2) take n =-3; s2 is true and ans is YES; BUT take n=-8, s2 is true but ans is NO ==> Insufficient

IMO A

hi,
explanation is amazing but can u explain statement 2 once again

if i take n=-3 then 1 / |-3| gives 1/3 which is not greater than 3, same way 1/|-8| gives 1/8 which is not greater than 8.

so how is this different?

[patanjali.purpose]

hi all,
pls assist in solving the below DS problem

If n is not equal to 0, is |n| < 4 ?

(1) n^2 > 16

(2) 1 / |n| > n

question implies IS -4<n<4?
(1) (n-4)(n+4) >0 ==> n>4; n<-4 ==> sufficient
(2) take n =-3; s2 is true and ans is YES; BUT take n=-8, s2 is true but ans is NO ==> Insufficient

IMO A

hi,
explanation is amazing but can u explain statement 2 once again

if i take n=-3 then 1 / |-3| gives 1/3 which is not greater than 3, same way 1/|-8| gives 1/8 which is not greater than 8.

so how is this different?

1/|-8| = 1/8 > (-8) == TRUE; BUT IS |-8| <4? NO. Therefore when we take n=-3, we get |n|<4, but when n=-8, we DO NOT GET |n|<4.

YES and NO for different number.

Hope it helps