integers n and p

[coffee5251]

If n and p are integers, is p > 0?

1. n+1 > 0

2. np > 0

OA C

I don't understand why the answer isn't B. If np > 0 doesn't that mean p > 0/n, which is p > 0? What am I missing?

Thanks for your help.

[dmateer25]

2. np > 0

You can plug in some numbers to see why this statement isn't sufficient.

Let's say n=1 and p=1

1(1) = 1

and 1>0 so this satisfies the statement and p would be greater than 0.

Now we can also try n=-1 and p=-1

(-1)(-1) = 1

and 1>0 so this satisfies the statement and p would be less than 0.


Therefore, statement 2 is insufficient.

[cramya]

I don't understand why the answer isn't B. If np > 0 doesn't that mean p > 0/n, which is p > 0? What am I missing

np > 0 means n and p are both positive or both negative. Stmt II does not tell us which case it is.

Stmt I

n+1 > 0
n>-1

n could be 0,1,2......

No info on p

Combined

n>-1
np>0

Since n is an integer n cant be 0 since np>0 so n has to be positive. If n is positive p has to be positive since np>0

Suff

Choose C)

Hope this helps also in addn to what Dmateer posted.

[cramya]

Hi Coffee,

Friendly request :Please post data sufficiency questions in the appropriate section of this forum.

Regards,
Cramya

[coffee5251]

Thanks for your help. Sorry about posting in the wrong forum- I hadn't even realized I'd done that. Oops

[calcpa2012]

Ah i GET IT

[sl750]

If n and p are integers, is p > 0?

1. n+1 > 0

2. np > 0

OA C

I don't understand why the answer isn't B. If np > 0 doesn't that mean p > 0/n, which is p > 0? What am I missing?

Thanks for your help.

you cannot divide by n here unless you are sure that it a positive number. Here it could be negative, that could change the sign, so you cannot perform such an operation