Sequence

I would go wiht B) OA?

yes it is, please explain now....

thanks
Andrew

Stmt I

Given: x1 x2 x3 x4 ...... x24

The third term in S is positive i.e x3 is positive

x1 and x2 could bothe be positive or x1 and x2 could both be negative. This does not lead us to a 1 definite answer for the number of negative terms

INSUFF

Stmt II


The fourth term in S is negative i.e x4 is negative

This means either x3 is negative x2 positive
(OR)
x3 is POSITIVE x2 NEGATIVE

Case 1
x1 x2 x3 x4 x5 x6
+ve - ve -ve +ve -ve

or

Case2

x1 x2 x3 x4 x5 x6
-ve +ve -ve -ve +ve

If u notice after x5 the signs alternate and there are 20 left of which 10 will be negative and 10 positive

We now have to figure out x1-x4 signs

Case 1
x1 x2 x3 x4
-ve +ve - ve -ve

If its case1 then x1 has to be -ve


Case2

x1 x2 x3 x4
-ve -ve +ve -ve

If its case2 then x1 still has to be -ve since x2 is neagtive and x3 is positive

So whether its case 1 or case 2 we know in x1-x4 ther's 3 nagatives and 1 positive

1 DEFINITE ANSWER for the number of negative terms

SUFF

Let me know if u still have questions (m hoping the format came out right for the x's)

Good luck!

The formatting dint come out as expected so reposting it (removing x1)

Stmt II


The fourth term in S is negative i.e x4 is negative

This means either x3 is negative x2 positive
(OR)
x3 is POSITIVE x2 NEGATIVE

Forget x1 for the time being
Case 1
x2 x3 x4 x5 x6
+ve - ve -ve +ve -ve

or

Case2

x2 x3 x4 x5 x6
-ve +ve -ve -ve +ve

If u notice after x5 the signs alternate and there are 20 left of which 10 will be negative and 10 positive

We now have to figure out x1-x4 signs

Case 1
x1 x2 x3 x4
-ve +ve - ve -ve

If its case1 then x1 has to be -ve


Case2

x1 x2 x3 x4
-ve -ve +ve -ve

If its case2 then x1 still has to be -ve since x2 is neagtive and x3 is positive

So whether its case 1 or case 2 we know in x1-x4 ther's 3 nagatives and 1 positive

1 DEFINITE ANSWER for the number of negative terms

SUFF

Let me know if u still have questions (m hoping the format came out right for the x's)

Good luck!