Hi meenes,
As a general rule, you can essentially "trust" a picture in a PS question (unless there's a statement telling you that the picture is NOT drawn to scale), but you should be a bit skeptical of any drawing that appears in a DS question.
This DS question includes a Number Line with the 4 variables placed at 'hash marks.' There are things that we DO know about the Number Line and things that we do NOT know:
We DO know that the 4 numbers are arranged from least to greatest (because that's how a Number Line "works"). However, we don't know the 'scale' of the line (and we have to consider the possibility that the 4 numbers are NOT evenly spaced out)...
For example, Q, R, S, and T could be 1, 2, 3 and 4
OR
Q, R, S, and T could be -1, 10, 19 and 2000.
Ultimately, with DS questions, you need facts/information to determine the exact nature of whatever picture is included. For example, if you have a picture of a triangle and you know that the sides of the triangle are 3, 4 and 5, then you know that you are dealing with a right triangle even if that is not clear from the picture (because there's no other type of triangle that can be formed with those 3 side lengths). However, If you have a picture of a right triangle and you know that the hypotenuse has a length of 5, then that does NOT necessary mean that you have a 3/4/5 (the two missing sides could be any two positive numbers that fit the Pythagorean Theorem A^2 + B^2 = 5^2).
GMAT assassins aren't born, they're made,
Rich
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