imane81 wrote:Please help on this one
The sum of the first 50 positive even integers is 2550. what is the sum of the even integers from 102 to 200 inclusive?
A. 5100
B. 7550
C. 10100
D. 15500
E. 20100
Sum = 2 x [51 + 52 + .... + 100]
Let the sum be 2x and solve. {Here x = [+ 52 + .... + 100 }
Apply the formula(sum of n natural no.s)
Sum of 1st 100 no.s = 100(100+1)/2 = 5050
Sum of 1st 50 no.s = 50(51)/2 = 1275
Hence we get x = 5050 - 1275 = 3775
Hence,the answer will be [spoiler]2 x 3775 = 7550 (B)[/spoiler]
Last edited by
harsh.champ on Thu Feb 18, 2010 12:44 pm, edited 1 time in total.
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