Bunuel wrote:
If a < b < c < d, is abcd > 0?
(1) abc > 0
(2) bcd < 0
Question: If a < b < c < d, is a*b*c*d > 0?
Answer to the question is YES if all variables are +ve or all variables are -ve or only two variables are +ve or -ve.
As per statement-1
a*b*c > 0, this can happen in two cases when all the variables are +ve or two variables are -ve.
So if a = 1, b =2 and c = 3 then d has to be greater than 3 as per question
or if a = -2 , b = -1 and c = 1 then d has to be greater than 2 (no variable in our case can be equal to "0").
In both the cases answer to our question is YES a*b*c*d > 0
So sufficient
As per statement-2
b*c*d < 0 , this can happen in two cases when all variables are -ve or only one variable is -ve.
If b = -1, c = 1, d = 2 then a has to be less than -1, So answer to the question is YES a*b*c*d > 0
If b = -3, c = -2, d = -1 then a has to be less than -3, Again answer to the question is YES a*b*c*d > 0
So sufficient.
(D)
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