Question Details

The number of persons who read magazine X only is thrice the number of persons who read magazine Y. The number of persons who read magazine Y only is thrice the number of persons who read magazine X. Then, which of the following conclusions can be drawn?
1. The number of persons who read both the magazines is twice the number of persons who read only magazine X.
2. The total number of persons who read either one magazine or both the magazines is twice the number of persons who read both the magazines.
Select the correct answer using the code given below:

Options

A

1 only

B

2 only

C

Both 1 and 2

D

Neither 1 nor 2

Show Answer

Correct Answer :

Option D

Neither 1 nor 2

Solution :

The correct answer is Neither 1 nor 2.

To understand why this is the correct choice, let us define the number of persons in each category using algebraic variables:
Let
a
be the number of persons who read magazine X only.
Let
b
be the number of persons who read magazine Y only.
Let
c
be the number of persons who read both magazines X and Y.

From these definitions, we can express the total number of persons who read each magazine:
The number of persons who read magazine X is:
a + c
The number of persons who read magazine Y is:
b + c

Now, we convert the statements given in the question into algebraic equations.

First Condition: "The number of persons who read magazine X only is thrice the number of persons who read magazine Y."
This gives us:
a = 3 ( b + c )
This can be expanded to:
a = 3 b + 3 c
(Equation 1)

Second Condition: "The number of persons who read magazine Y only is thrice the number of persons who read magazine X."
This gives us:
b = 3 ( a + c )
This can be expanded to:
b = 3 a + 3 c
(Equation 2)

Let us solve the system of equations by subtracting Equation 2 from Equation 1:
a - b = ( 3 b + 3 c ) - ( 3 a + 3 c )
Simplifying the right side:
a - b = 3 b - 3 a
Rearranging the terms:
4 a = 4 b a = b

Substituting
a=b
back into Equation 1:
a = 3 a + 3 c
Subtracting
3a
from both sides:
- 2 a = 3 c
Solving for
c
:
c = - 2 3 a

Since the number of persons in any category cannot be negative (
a0
and
c0
), the only mathematically valid solution is:
a = b = c = 0
In any scenario with a non-zero reader base, these conditions are contradictory. Thus, no consistent positive integer solution exists.

Even if we analyze the assertions based on the relations:
Evaluating Conclusion 1: "The number of persons who read both the magazines is twice the number of persons who read only magazine X."
This requires
c=2a
. However, our derivation shows that
c=-23a
. Therefore, Conclusion 1 does not hold.

Evaluating Conclusion 2: "The total number of persons who read either one magazine or both the magazines is twice the number of persons who read both the magazines."
The total number of persons is
a+b+c
. Since
a=b
, the total is
2a+c
.
For this conclusion to be correct:
2 a + c = 2 c 2 a = c
This also contradicts our relationship where
c=-23a
. Thus, Conclusion 2 does not hold.

Consequently, neither Conclusion 1 nor Conclusion 2 can be logically drawn.

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