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Data sufficiency

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Data sufficiency

by Newaz111 » Mon May 04, 2015 4:07 am
For each positive integer n, the integer n* is defined by n* = n^2 + 1. What is the value of the positive integer k ?

(1) when k is divided by 4, the reminder is 1.
(2) 18<k*<36

In statement '2' 18 is less than or equal to k* and K* is less than or equal 36. I didn't found that symbol, sorry for that.

Thank You...:)


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by Uva@90 » Mon May 04, 2015 6:04 am
Newaz111 wrote:For each positive integer n, the integer n* is defined by n* = n^2 + 1. What is the value of the positive integer k ?

(1) when k is divided by 4, the reminder is 1.
(2) 18<k*<36

In statement '2' 18 is less than or equal to k* and K* is less than or equal 36. I didn't found that symbol, sorry for that.

Thank You...:)

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Hi,
Is OA B ?

Please post OA along with Question.

Here is how I did,

Stmt 1: 5 and 9 are two possible values of K.hence insufficient.

Stmt 2:

18<= k^2+1 <= 36

Substitute values for K

K =4 ==> K^2 +1 = 17 hence not possible.
K =5 ==> K^2+1 = 26 YES possible.
K =6 ==> K^2+1 = 37 not possible.

Hence K = 5
Sufficient.

So OA is B

Regards,
Uva.
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by Brent@GMATPrepNow » Mon May 04, 2015 7:27 am
Newaz111 wrote:For each positive integer n, the integer n* is defined by n* = n² + 1. What is the value of the positive integer k ?

(1) When k is divided by 4, the reminder is 1.
(2) 18 < k* < 36
Target question: What is the value of the positive integer k?

Statement 1: When k is divided by 4, the reminder is 1.
There are MANY MANY possible values of k that satisfy statement 1.
Some possible values of k include 1, 5, 9, 13, etc
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: 18 < k* < 36
Let's examine some possible values of k* by testing some positive integers.
1* = 1² + 1 = 2 [not within the range of 18 < k* < 36]
2* = 2² + 1 = 5 [not within the range of 18 < k* < 36]
3* = 3² + 1 = 10 [not within the range of 18 < k* < 36]
4* = 4² + 1 = 17 [not within the range of 18 < k* < 36]
5* = 5² + 1 = 26 [WITHIN the range of 18 < k* < 36]
6* = 6² + 1 = 37 [not within the range of 18 < k* < 36]
7* = 7² + 1 = 50 [not within the range of 18 < k* < 36]

If 18 < k* < 36, then we can see that k must equal 5
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer = B

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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