Carcass wrote:
Given that the sum of the odd integers from 1 to 49 is k, what is the sum of the even integers from 2 to 50 in terms of k?
Let
2 + 4 + 6 + 8 + . . . . . + 46 + 48 + 50 = x [notice that there are 25 terms in this sum]Given: 1 + 3 + 5 + 7 + . . . . .+ 45 + 47 + 49 = k [notice that there are 25 terms in this sum as well] Subtract the bottom equation from the top equation to get:
1 + 1 + 1 + 1 + . . . . . + 1 + 1 + 1 = x - kSince the left side of both equations has 25 terms, the equation simplifies to get:
25 = x - kAdd k both sides of the equation:
25 + k = xAnswer: 25 + k
ASIDE: You would never see a Numeric Entry question like this on test day, Numeric Entry questions don't have non-numeric answers.