A certain list consists of several diff integers. Is the

Question

A certain list consists of several diff integers. Is the product of all the integers in the list positive?

1) The product of the greatest and smallest of the integers in teh list is positive
2) There is an even number of integers in the list


I couldn't agree with the OA.

wshaffer · Answer

B.

S1 There could be three numbers in the list, -12, -11, -10 and the product of -12 and -10 would be 120 but the product of all three numbers would be -1,320. Alternatively, a list consisting of: 10, 11, 12 would yield 10*12 = 120 and 12*11*10 = 1,320. Insufficient

S2 If there is an even number of integers, whether positive or negative, the product of the first and last numbers and the product of all of the numbers will be positive. Ex. 2*3*4*5 = 120 and 2*5 = 10. Or, -2*-3*-4*-5 = 120 and -2 * -5 = 10. Sufficient.

lfox2 · Answer

From A
We know that the list contains all positive or negative, and does not contain ZERO (an integer). We don't know if the list of numbers is odd or even. INSUFF

From B
We only know that the list contains an even amount of numbers, BUT we do not know if the list starts with a negative and ends with an positive number. Nor do we know if the list contains a ZERO. INSUFF

From both we have what we need
 1) Combination from A the list does not contain zero and is either - or +
 2) The list of numbers is even

SUFF - My answers is C? What is the OA?

Viperace · Answer

Are you assuming that the sign of those numbers are in some kind of pattern ?
-,-,-,+,+,+

lfox2 · Answer

From B
We only know that the list contains an even amount of numbers, BUT we do not know if the list starts with a negative and ends with an positive number. Nor do we know if the list contains a ZERO. INSUFF

RODUCT OF ALL IS ZERO OR -4,-3,-2,-1

RODUCT OF ALL IS POSTIVIE OR 5,6,7,8

RODUCT OF ALL IS POSTIVIE They all contain an even number of numbers but ZERO is neither postive or negative BUT it is an integer!

Viperace · Answer

Allright, I see what have I been missing now. 
So, the list is  consecutive . If this is the case, then I am fine with the answer C. 

But, the question did not specify whether the integers are consecutive or not! Do we need to make this assumption ourselves when we see the word 'list' ?

yezz · Answer

A certain list consists of several diff integers. Is the product of all the integers in the list positive? 

1) The product of the greatest and smallest of the integers in the list is positive 
2) There is an even number of integers in the list 

this is true only if all the terms are +ve or the number of negative terms is even

from one

clearly insuff ( we have no idea about the other terms and there numbers ( even or odd)


the two inegers could be both -ve or both positive AND ZERO IS NOT IN THE LIST



from two

even number of intigers..........no info about the number of -ve termsAND ANY TERM COULD BE ZERO

not suff

both together

i see suff

two first intigers with the same sign and the number is even ....enough, any term could NOT = zero

my answer is C

anindyat · Answer

Will go for C

From 1) 
If -,-,-..then product of first and last is + ve but product of all negative

From 2)
it says even elements 
alone not sufficient

Together
Suff

C

Viperace · Answer

OA is indeed, C I think I knew whats wrong with my understanding. A list means a list .

The numbers followed accordingly (from small to large or vice versa).

A certain list consists of several diff integers. Is the

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