If S is a data set of three numbers x, y and z, is the range of the numbers in S less than 2?
(1) x - y < 1
(2) y - z < 2
If S is a data set of three numbers x, y and z, is the range
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You can solve this problem by testing numbers.BTGmoderatorDC wrote:If S is a data set of three numbers x, y and z, is the range of the numbers in S less than 2?
(1) x - y < 1
(2) y - z < 2
(1) x - y < 1
This tell us that the distance between x and y is less than 1, but it gives us no information about z, so we can't know anything about the range of the set. Insufficient.
(2) y - z < 2
This tells us that the distance between y and z is less than 2, but tells us nothing about x, so again we can't make any inferences about the range. Insufficient.
(1) & (2) together
Try testing values that fit both statements: the distance between x and y is less than 1, and the distance between y and z is less than 2.
Case 1: values close together
x = 0.5
y = 0.4
z = 0.3
The range = 0.2, so the answer to the question is "yes".
Case 2: try to pick values that are further apart to see if you can get a range greater than 2:
x = 2.9
y = 2
z = 0.1
The range = 2.8, so the answer to the question is "no."
If we can sometimes get a "yes" and sometimes a "no," then the statements together are still insufficient.
The answer is E.
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
EdM in Mind, Brain, and Education
Harvard Graduate School of Education