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Set A contains all the even numbers..........

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Set A contains all the even numbers..........

by pzazz12 » Wed Oct 06, 2010 10:59 pm
Set A contains all the even numbers between 2 and 50 inclusive. Set B contains all the even numbers between 102 and 150 inclusive. What is the difference between the sum of elements of set B and that of set A?

A. 2500
B. 5050
C. 11325
D. 6275
E. 2550
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by Rahul@gurome » Wed Oct 06, 2010 11:31 pm
The sum of all elements in set B is 102+104+106....150.
The sum of all elements in set A is 2+4+6......50.
The difference is (102+104+106....150) - (2+4+6......50)
= (102-2) + (104-4) ..........+(150-50)
=100 *25 = 2500.

The correct answer is A.
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by saurabhmahajan » Thu Oct 07, 2010 2:02 am
By formula

to find total numbers of evens in set A = [50-2 / 2] + 1 = 25 even numbers
to find sum of these even numbers, find average of this set = [50 + 2] / 2= 26
now multiply these two results to get sum= 25 * 26 = 650 (2 + 4 + 6+.....+50 = 650)

perform the same operation on set B na dyou will get total as 3150
now 3150 - 650 = 2500
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by pzazz12 » Sat Oct 09, 2010 12:06 am
Rahul@gurome wrote:The sum of all elements in set B is 102+104+106....150.
The sum of all elements in set A is 2+4+6......50.
The difference is (102+104+106....150) - (2+4+6......50)
= (102-2) + (104-4) ..........+(150-50)
=100 *25 = 2500.

The correct answer is A.


thank you Rahul....
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