Lessons

General Aptitude
9.1 Numbers - General Questions

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Q.

The sum of even numbers between 1 and 31 is:

View Answer

Correct choice: C

Explanation:

Let Sn = (2 + 4 + 6 + ... + 30). This is an A.P. in which a = 2, d = 2 and l = 30

Let the number of terms be n. Then,

a + (n - 1)d = 30

     2 + (n - 1) x 2 = 30

    n = 15.

Sn = n (a + l) = 15 x (2 + 30) = (15 x 16) = 240.
2 2
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