simple problem, but i just don't get it

G

Guest

Guest
hi,

i'm studying for the gre, and the problem below was on a practice test. luckily, there are explanations at the end of the test of each problem, but i still don't understand how to solve this.

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Given integer c, how many integers are greater than c and less than 2c?
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ans. c-1
 
Hello, bethany!

Given integer c, how many integers are greater than c and less than 2c?
Click to expand...
The very least you can do is to try some examples.

Suppose c = 6.
. . How many integers are between 6 and 12?
. . 7, 8, 9, 10, 11 . . . five.

Suppose c = 20.
. . How many integers are between 20 and 40?
. . 21, 22, 23, ... , 39 . . . nineteen.

Suppose c = 100.
. . How many integers are between 100 and 200?
. . 101, 102, 103, ...., 199 . . . ninety-nine.

Are you getting a pattern?
 
soroban said:
Are you getting a pattern?
Click to expand...

Yes! Now I understand why the answer is c-1. The explanation from the test is so much more difficult...makes me want to jump out the window. Thanks for your help!

:D
 
Given integer c, how many integers are greater than c and less than 2c?

C, C+1, C+2, C+3.....,(2C)-1,2C

think about the above sequence of these values
the number of values between c and 2c will always be one less than c
therfore the number of intergers between them is (c-1)

a more symbolic approach... :

roll:
 
try the concept of absolute values for the perfect solution if this detail is required.....

( l C l - 1) is the solution...................
 
Ahhh, but for the perfect solution you must include the possibility that c = 0, a very nice integer. APMs right about needing absolute values but he's not quite there yet. One more function will do it :twisted:
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I hope this messes things up
Gene
 
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