binskyba Posted August 25, 2011 Share Posted August 25, 2011 At a certain financial institution, 30% of the clients use both credit card and a cheque book, but 40% of the clients who use the credit card do not use the cheque book. What percentage of the members of the institution use the credit card? A. 35 B. 40 C. 50 D. 65 E. 75 Pleas help me and give me a nice explanation, of course an explanation which takes less than 2 min. to do. THNKS Quote Link to comment Share on other sites More sharing options...
missionGMAT Posted August 26, 2011 Share Posted August 26, 2011 IMO C. Let the total clients = 100 No. of clients using both credit card and cheque book = 30. Let total no of clients using credit card = x So, no. of clients using credit card but no cheque book = 0.4x According to question, 0.4x+30 = x x= 50 (which is the total number of clients using credit card) Since we had assumed total no. of client to be 100, this value of x is the percentage answer. You can aslo do it by making table as: CC no CC Total CB 30 no CB 0.4x Total x 100 It took little less than a min to solve this. I hope this was helpful. Quote Link to comment Share on other sites More sharing options...
Brent Hanneson Posted August 27, 2011 Share Posted August 27, 2011 MissionGMAT's solution is perfect. However, some students benefit from organizing the information in a more visual manner. This is where the Double Matrix Method comes in. For questions involving a population of things (this time a population of clients) where each thing has two characteristics associated with it (here the 2 characteristics are: 1) having/not having credit card, and 2) having/not having cheque book), we can solve the question using the Double Matrix method. For a free lesson on the Double Matrix Method, watch video #20 at GMAT Word Problems | GMAT Prep NowAfterwords you can tackle the practice questions #21 and #44 on the same page. Cheers, Brent Quote Link to comment Share on other sites More sharing options...
binskyba Posted August 29, 2011 Author Share Posted August 29, 2011 Thank you very much! Quote Link to comment Share on other sites More sharing options...
Masuraha Posted September 27, 2011 Share Posted September 27, 2011 Answer = 50. Please let me know if that is correct and I can provide the explanation. Quote Link to comment Share on other sites More sharing options...
800 Posted October 3, 2011 Share Posted October 3, 2011 I think, for question with 2 yes/no options (like credit card y/n and cheque y/n) double matrix is the best option (given that the question is long!). for short question (but tricky) like this one, we can (also) go for calculation as follows - 30% uses both credit card and cheque. 40% of the credit card users (the tricky part) does not use cheque. SO, (100-40)% or 60% of credit card user uses cheque. SO, 60% of credit card user is equal to 30% of total member of the institute. SO, 100% of credit card user is 50% of the total member of the institute. It is C. (50%) Quote Link to comment Share on other sites More sharing options...
alok_nayak Posted October 18, 2011 Share Posted October 18, 2011 30% of Total use both credit card and cheque book 40% of those who use credit card do not use cheque book so, 60% of those who use credit card use both credit card and cheque book or, 60% of those who use credit card = 30% of Total so, 40% of those who use credit card = 20% of Total so, 100% of those who use credit card = 50% of Total Quote Link to comment Share on other sites More sharing options...
Masuraha Posted October 31, 2011 Share Posted October 31, 2011 Let the total percentage of credit card users be c% Since 40% of credit card users do not use cheque book, so the equation will be .4c/100 = (c/100) - (.3) Solving we get c = 50 Quote Link to comment Share on other sites More sharing options...
lonelygmatprep Posted November 16, 2011 Share Posted November 16, 2011 I don't understand how to use the double matrix for it? can anyone explain? Quote Link to comment Share on other sites More sharing options...
Masuraha Posted December 2, 2011 Share Posted December 2, 2011 I agree with answer as 50. You can use Venn diagram to determine the same. Quote Link to comment Share on other sites More sharing options...
Vishwa Hegde Posted August 26, 2012 Share Posted August 26, 2012 MissionGMAT's solution is perfect. However, some students benefit from organizing the information in a more visual manner. This is where the Double Matrix Method comes in. For questions involving a population of things (this time a population of clients) where each thing has two characteristics associated with it (here the 2 characteristics are: 1) having/not having credit card, and 2) having/not having cheque book), we can solve the question using the Double Matrix method. For a free lesson on the Double Matrix Method, watch video #20 at GMAT Word Problems | GMAT Prep NowAfterwords you can tackle the practice questions #21 and #44 on the same page. Cheers, Brent The Double Matrix method is really helpful! Thanks! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.