Came back to the question again:(
Quote:
Material A costs $3 per kilogram, and material B costs $5 per kilogram. If
10 kilograms of material K consists of x kilograms of material A and y
kilograms of material B, is x > y?
(1) y > 4
(2) The cost of the 10 kilograms of material K is less than $40.
OE says:
Since x + y = 10, the relation x > y is equivalent to
x > 10 – x, or
x > 5.(1) The given information is consistent with
x = 5.5 and y = 4.5, and the given
information is also consistent with
x = y = 5.Therefore, it is possible for x > y to be true
and it is possible for x > y to be false; NOT
sufficient.
How can we take the case of x = y = 5 when we know x>5??