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PYQ Question

A Question if given followed by two Statements I and II. Consider the Question and the Statements. Question : Is (x+y) an integer? Statement-I : (2x+y) is an integer. Statement-II : (x+2y) is an integer. Which one of the following is correct in respect of the above Question and the Statements?

A Question if given followed by two Statements I and II. Consider the Question and the Statements. Question : Is (x+y) an integer? Statement-I : (2x+y) is an integer. Statement-II : (x+2y) is an integer. Which one of the following is correct in respect of the above Question and the Statements?
  1. A. The Question can be answered by using one of the Statements alone, but cannot be answered using the other Statement alone
  2. B. The Question can be answered by using either Statement alone
  3. C. The Question can be answered by using both the Statements together, but cannot be answered using either Statement alone
  4. D. The Question cannot be answered even by using both the Statements together

Answer: D

Explanation

We need to determine if (x+y) is an integer.

**Statement I: (2x+y) is an integer.**
– Let x = 0.5, y = 1. Then 2x+y = 2(0.5)+1 = 1+1 = 2 (integer). But x+y = 0.5+1 = 1.5 (not an integer).
– Let x = 1, y = 1. Then 2x+y = 2(1)+1 = 3 (integer). And x+y = 1+1 = 2 (integer).
Since (x+y) can be an integer or not, Statement I alone is insufficient.

**Statement II: (x+2y) is an integer.**
– Let x = 1, y = 0.5. Then x+2y = 1+2(0.5) = 1+1 = 2 (integer). But x+y = 1+0.5 = 1.5 (not an integer).
– Let x = 1, y = 1. Then x+2y = 1+2(1) = 3 (integer). And x+y = 1+1 = 2 (integer).
Since (x+y) can be an integer or not, Statement II alone is insufficient.

**Combining Statement I and Statement II:**
We have: (2x+y) = K (an integer) and (x+2y) = M (an integer).
Adding these two equations: (2x+y) + (x+2y) = K + M
3x + 3y = K + M
3(x+y) = K + M.
Since K and M are integers, K+M is also an integer. So, 3(x+y) is an integer.
However, if 3(x+y) is an integer, (x+y) itself is not necessarily an integer. For example, if x=1/3 and y=1/3:
– 2x+y = 2/3 + 1/3 = 1 (integer).
– x+2y = 1/3 + 2/3 = 1 (integer).
– But x+y = 1/3 + 1/3 = 2/3 (not an integer).
Therefore, even with both statements combined, we cannot definitively say if (x+y) is an integer. This question tests data sufficiency and properties of integers and rational numbers.