If k is a positive integer and the tens digit of k+5 is 4

Question

If k is a positive integer and the tens digit of k+5 is 4, what is the tens digit of k?

(1) k > 35
(2) The units digit of k is greater than 5

Does it mean it can be: 
36, 37 ... 44. from (1) statement and 36, 37, 38 and 39 from the (2) statement. 
and k is 3?

udaymathapati · Answer

Hi, It's been asked about tens digit of K+5=4 hence its possible to have 4 as answer.... Answer should be B. My explanation for the answer as follows; 1. K>35 Stmt one satisfies many numbers starting from 36 till 44 where tens digit of k+5 is 4 (E.g. 36+5=41, 37+5=42....41+5=46). Here tens digit of K has two options either 3 or 4 hence can't answer uniqure number K. 2. Unit Digit of K is >5 For this we have only 4 options available which satisfies tens digit of k+5=4 condition. Numbers are 36, 37, 38 and 39. All these 4 numbers have only one unique number as tens digit i.e. 3 Hence we got our answer. Hence B is suff to answer the question. If you like explanation, consider for kudos.... :-D

Anonymous · Answer

Question stem says 40 <= k+5 <= 49, thus 35 <= k <= 44
Statement 1 says k > 35, thus 36 <= k <= 44. Tens digit could be 3 or 4, insufficient
Taking into account the range of k provided in the question stem, statement 2 says that 36 <= k <= 39. Units digit must be 3, sufficient
Answer B

Bunuel · Answer

If k is a positive integer and the tens digit of k+5 is 4, what is the tens digit of k?

Translate the stem: "the tens digit of k+5 is 4" -->  40\leq{k+5}\leq{49}  -->  35\leq{k}\leq{44}  --> so the tens digit of  k  could be 3 or 4.

Side note: strictly speaking  k  could be more than two digit number (for example 3-digit  x40\leq{k+5}\leq{x49}  ), though as we are interested only in units and tens digit then this wouldn't change anything and we can neglect other digits.

(1) k > 35 --> just tells us that  k
eq{35} , so we have  35<{k}\leq{44}  --> the tens digit of  k  could still be 3 or 4. Not sufficient.

(2) The units digit of k is greater than 5 -->  k  could only be 36, 37, 38, 39 --> so the tens digit of  k  is 3. Sufficient.

Answer: B.

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

If k is a positive integer and the tens digit of k+5 is 4

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards