CAT 2003 Slot 1QA Question 24

Infinite Geometric ProgressionEasy
Passage / Data

Each question is followed by two statements, A and B. Answer each question using the following instructions

Choose 1 if the question can be answered by using one of the statements alone but not by using the other statement alone.
Choose 2 if the question can be answered by using either of the statements alone.
Choose 3 if the question can be answered by using both statements together but not by either statement alone.
Choose 4 if the question cannot be answered on the basis of the two statements.

Each question is followed by two statements, A and B. Answer each question using the following instructions

Choose 1 if the question can be answered by using one of the statements alone but not by using the other statement alone.
Choose 2 if the question can be answered by using either of the statements alone.
Choose 3 if the question can be answered by using both statements together but not by either statement alone.
Choose 4 if the question cannot be answered on the basis of the two statements.

Is (1a2+1a4+1a6+...)>(1a+1a3+1a5+...)?


A. −3 ≤ a ≤ 3
B. One of the roots of the equation 4x2 − 4x + 1 = 0 is a

Answer & solution

  • 1

  • B

    2

  • C

    3

  • D

    4

Solution

R.H.S. and L.H.S. are infinite GP's with common ratio = 1a2.

∴ We need to find whether

1a21-1a2<1a1-1a2

1a2>1a ...(i)

This statement (i) is always true for a < 1.

Using statement A alone:

It does not give any conclusion regarding value of a i.e. whether it is less than 1 or not.

So, statement A alone is not sufficient to answer the question.

Using statement B alone:

4a2 − 4a + 1 = 0                                   …(ii)

∴ a = 1/2

So, statement B alone is sufficient to answer the question.

Hence, option (a).

CAT 2003 Slot 1 QA Q24: Each question is followed by two statements, A and B. Answer each question using the following instructions Ch — Solution | TheCATExam