Question #1f547

1 Answer
Jan 13, 2018

Set the first number to some variable nn and write all the other 44 numbers in terms of nn, equate the sum to 310310, solve for nn, then solve for the third number in terms of nn to get 6262.

Explanation:

Let's set the first even number to nn. Since we have 55 consecutive numbers, the second should be n + 2n+2, the third is n + 4n+4, fourth is n + 6n+6, and finally fifth is n + 8n+8. We know that they add up to 310310:

n + (n + 2) + (n + 4) + (n + 6) + (n + 8) = 310n+(n+2)+(n+4)+(n+6)+(n+8)=310

Let's simplify, adding up like terms (add up all the nns, and add up all the numbers):

5n + 20 = 3105n+20=310

Subtract each side by 2020:

5n + 20 - 20 = 310 - 205n+2020=31020

5n = 2905n=290

Now we can divide by 55:

(5n)/5 = 290/55n5=2905

n = 58n=58

Since we know the first number, n = 58n=58, and we know that the third number is n + 4n+4, simply figure out what n + 4n+4 is:

n + 4 = 58 + 4 = 62n+4=58+4=62

Therefore the third number in the sequence is 6262.