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If a equals the sum of the even integers from 2 to 200, inclusive, and
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Updated on: 24 Oct 2014, 02:15
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If a equals the sum of the even integers from 2 to 200, inclusive, and b equals the sum of the odd integers from 1 to 199, inclusive, what is the value of a  b? A. 10 B. 100 C. 190 D. 200 E. 210
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Originally posted by Drik on 06 Jan 2013, 00:24.
Last edited by Bunuel on 24 Oct 2014, 02:15, edited 2 times in total.
Edited the question.



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Re: If a equals the sum of the even integers from 2 to 200, inclusive, and
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06 Jan 2013, 01:09
Drik wrote: If a equals the sum of the even integers from 2 to 200, inclusive, and b equals the sum of the odd integers from 1 to 199, inclusive, what is the value of a  b? [*]10 [*]100 [*]190 [*]200 [*]210 Number of even integers from 2 to 200, inclusive is \((2002)/2 + 1\) or \(198/2 + 1\) or \(100\). Mean of evenly spaced set that includes all the even numbers from 2 to 200 inclusive is \((200+2)/2\) or \(101\). Therefore a= \(101*100\) Number of odd integers from 1 to 199, inclusive is \((1991)/2 + 1\) or \(198/2 +1\) or \(100\). Mean of evenly spaced set that includes all the odd numbers from 1 to 199, inclusive is \((199+1)/2\) or \(100\). Therefore b=\(100*100\) hence ab=\((100 * (101100))\) or \(100\) +1B
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Re: If a equals the sum of the even integers from 2 to 200, inclusive, and
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07 Jan 2013, 01:05



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Re: If a equals the sum of the even integers from 2 to 200, inclusive, and
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13 Jan 2015, 19:28
PROBLEM: If a equals the sum of the even integers from 2 to 200, inclusive, and b equals the sum of the odd integers from 1 to 199, inclusive, what is the value of a  b?
A. 10 B. 100 C. 190 D. 200 E. 210
SOLUTION:
Use following formulae for such problems:
Sum of evenly spaced integers = (# of integers)*(mean of integers)
# of integers = [(last  first)/2] + 1 Mean of integers = (last + first)/2
In above problem:
# of integers = [(200  2)/2] + 1= 100 and [(1991)/2]+ 1 = 100 Mean of integers = (200 + 2) = 101 and (199 + 1)/2 = 100
Sum of integers = (101*100) = 10100 and (100*100) = 10000
Thus their difference (a  b) = 100
ANSWER:B



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Re: If a equals the sum of the even integers from 2 to 200, inclusive, and
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13 Jan 2015, 20:07
Hi All, When a GMAT Quant question asks you to deal with a big group of numbers, there's almost always a builtin pattern that can help you to avoid a lengthy "math approach." Here, we're given two groups: Group A = the sum of all the EVEN integers from 2 to 200, inclusive Group B = the sum of all the ODD integers from 1 to 199, inclusive We're asked for the value of A  B Calculating any of these individual totals would take some work, but notice how the two groups follow a pattern: (The first term in A)  (The first term in B) = 2  1 = 1 (The second term in A)  (The second term in B) = 4  3 = 1 This pattern will continue as you compare each successive term in each group Since we're dealing with just the even numbers in Group A, 200/2 = 100 total terms. This means that we'll have 100 differences of "1" The Total difference will be 100(1) = 100 Final Answer: GMAT assassins aren't born, they're made, Rich
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Re: If a equals the sum of the even integers from 2 to 200, inclusive, and
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23 Mar 2015, 01:59
A: 2,4,6,8,10,12,14
B: 1,3,5,7, 9, 11,13
see that every number in A is exactly 1 more than such number in B.
difference is exactly the number of term in A and B and it is 100
B



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Re: If a equals the sum of the even integers from 2 to 200, inclusive, and
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30 Dec 2015, 06:52
if we have 100 even and 100 odd then the difference between the sum of even ones and odds one will be 100. logically thinking, each even number will be 1 more than preceded odd number. since we have 100 even numbers, then the difference is 100.



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Re: If a equals the sum of the even integers from 2 to 200, inclusive, and
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Re: If a equals the sum of the even integers from 2 to 200, inclusive, and
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