On the number line above, is the product of w, x, y, and z negative?
(1) z is positive.
it gives no info about the nature of sign of w, x, y . hence
insufficient.(2) The product of w and x is positive
it means either :
i)both w & x are positive : now y and z should also be positive, since they are on right side of w & x. hence product is
positive.ii)or both w & x are negative.: here there are 3 cases,
a) w, x, y, z = negative. product = positive
b) w, x, y = negative, z = positive. product = negative.
c) w, x= negative, y, z = positive. product = positive.
Hence
insufficient.No even after combining St 1 & 2 , we get
w, x, y = negative, z = positive. product = negative.
OR, w, x= negative, y, z = positive. product = positive.
so it is still
INSUFFICIENT.Answer = E
adkikani wrote:
Quote:
On the number line above, is the product of w, x, y, and z negative?
(1) z is positive.
it gives no info about the nature of sign of w, x, y . hence
insufficient.(2) The product of w and x is positive
Please validate below approach:
Clearly statements when individually taken are insufficient.
When together:
Product of w and x is positive, implies either both w and x are positive or
both are negative. Now since y lies between x and z, it can take a positive or
negative value. Hence irrespective of z being positive, we can still have final product
as positive or negative.
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