help on quant - several problems

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help on quant - several problems

by stephkhaira » Mon Aug 26, 2013 4:50 pm
Help on these problems would be appreciated!

1) Loan X has a principal of 10000x and simple annual interest of 4%. Loan Y has a principal of 10000Y and simple annual interest of 8%. Both loans will be consolidated into loan Z, where the principal is (10000x+10000y) and simple interest is r%, where r=(4x+8y)/(x+y). What are x and y for r=.05? ANSWERS: x=96, y=32

2) What is the value of x? 2^x - 2^(x-2) = 3*(2^13)
ANSWER: X=15

3) 6 machines work at the same constant rate and it takes them 12 days to complete 1 job. If the job must be done in 8 days, how many machines should be added?
ANSWER: 3

4) (Similar as above) Each of 10 machines works at the same constant rate. Together they complete a job in 16 hours. How many hous does it take 8 machines to finish the job?
ANSWER: 20

5) The number of stamps Kyle had and the number of stamps Amy had were in a ratio of 5:3 respectively. After Kyle gave Amy 10 stamps, the ratio changed to 7:5. As a result of the gift, Kyle had how many more stams than Amy?
ANSWER: 40

6) Codes can be formed by 1, 2 or 3 letters from the 26-letter alphabet. If letters can be repeated and if the same letters in different order are taken as different codes, then how many codes can be formed?
ANSWER: 18278

7) For all 1<=k<=10, the kth term of a sequence is (-1)^(k+1) * (1/2^k). If T is the sum of the first 10 terms in the sequence, then T is
a) Greater than 2
b) Between 1 and 2
c) Between 0.5 and 1
d) Between .25 and .5 (right answer)
e) Less than .25
Source: — Problem Solving |

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by Brent@GMATPrepNow » Mon Aug 26, 2013 5:38 pm
Please post only one question per thread. Otherwise things can become pretty complicated when there are discussions on multiple questions.

Also, when posting questions, please use the spoiler function to hide the correct answer. This will allow others to attempt the question without seeing the final answer.


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by Brent@GMATPrepNow » Mon Aug 26, 2013 5:53 pm
Also, when you repost the questions, please be sure to include the answer choices.
In many instances, the best (fastest) approach it to use the answer choices to your advantage.
This is particularly true with your counting question
6) Codes can be formed by 1, 2 or 3 letters from the 26-letter alphabet. If letters can be repeated and if the same letters in different order are taken as different codes, then how many codes can be formed?
Cheers,
Brent
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by stephkhaira » Mon Aug 26, 2013 6:40 pm
Thanks Brent!

I have already reposted the questions separately, and included the options as well as hid the right answer.
As you may have noticed this was my first post in the forum, so I wasn't quite sure what was the best way to proceed.

Best,
Steph.

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by Brent@GMATPrepNow » Mon Aug 26, 2013 6:51 pm
No problem - thanks for reposting.
And welcome to BTG!

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