DS sequence.

[rakeshd347]

Given a sequence: a1,a2,a3,a4......

In the sequence shown,an=(an-1)+k , where 2<=n<=15 and k is a nonzero constant. How many of the terms in the sequence are greater than 10?

(1) a1=24
(2) a8=10

OA coming soon.


Just to clarify
an= nth term of the sequence and
an-1= n-1th term of the sequence.

[theCodeToGMAT]

Given a sequence: a1,a2,a3,a4......
In the sequence shown,an=(an-1)+k , where and k is a nonzero constant. How many of the terms in the sequence are greater than 10?

(1) a1=24
(2) a8=10

To find --> Terms > greater than 10

K can be +ve or -ve
We have Info of "N"

Statement 1:
we don't know about "k"..
Insufficient

Statement 2:
A8 = 10
We have info of "N" .. 8th is the middle term.. so "7 terms" is the answer
SUFFICIENT,

Answer [spoiler]{B}[/spoiler]

[rakeshd347]

Given a sequence: a1,a2,a3,a4......
In the sequence shown,an=(an-1)+k , where and k is a nonzero constant. How many of the terms in the sequence are greater than 10?

(1) a1=24
(2) a8=10

To find --> Terms > greater than 10

K can be +ve or -ve
NO Info of "N"

Statement 1:
we don't know about "k"..
Insufficient

Statement 2:
A8 = 10
No info of "N"
INSUFFICIENT,

Combining...
Sufficient.

Answer [spoiler]{C}[/spoiler]

What is the OA???

This one is tricky and tough. Try again wrong answer.

[rakeshd347]

Given a sequence: a1,a2,a3,a4......
In the sequence shown,an=(an-1)+k , where and k is a nonzero constant. How many of the terms in the sequence are greater than 10?

(1) a1=24
(2) a8=10

To find --> Terms > greater than 10

K can be +ve or -ve
NO Info of "N"

Statement 1:
we don't know about "k"..
Insufficient

Statement 2:
A8 = 10
No info of "N"
INSUFFICIENT,

Combining...
Sufficient.

Answer [spoiler]{C}[/spoiler]

What is the OA???

This one is tricky and tough. Try again wrong answer.

Sorry my bad. i missed one part of the question try again.

[theCodeToGMAT]

Sorry my bad. i missed one part of the question try again.

ohk , then the Answer must be [spoiler]{B}[/spoiler]
Solution Updated!

[GMATGuruNY]

a(1), a(2),...., a(15)
In the sequence shown, a(n) = a(n-1) + k, where 2≤n≤15 and k is a nonzero constant. How many of the terms in the sequence are greater than 10?

1) a(1)=24
2) a(8)=10

Statement 1 is clearly insufficient.

Statement 2: a₈ = 10.
If k>0, then the sequence is INCREASING: each term in the sequence is GREATER than the preceding term.
In this case, a₉...a�₅ -- a total of 7 terms -- will be greater than 10.
If k<0, then the sequence is DECREASING: each term in the sequence is LESS than the preceding term.
In this case, a�...a₇ -- a total of 7 terms -- will be greater than 10.
In each case, the number of terms greater than 10 = 7.
SUFFICIENT.

The correct answer is B.