Q: If X is the sum of first 40 positive even integers and Y is the sum of first 40 positive odd integers, what is the value of x-y?
Please try to explain your answers
Options:
(A) 0
(B) 25
(C) 40
(D) 75
(E) 100
A: OK... Stream of consciousness: First even minus first odd = 2-1 = 1;
The sum of first 2 even integers minus the sum of first 2 odd integers = (2+4)-(1+3) = 2;
The sum of first 3 even integers minus the sum of first 3 odd integers = (2+4+6)-(1+3+5) = 3;
We can see the patterns here, so the sum of first 40 positive even integers minus the sum of first 40 positive odd integers will be 40.
The answer is (C).

Q: A no. when divided by the sum of 555 and 445 gives 2times their difference as quotient & 20 as remainder. Find the no. is?
Options:
(A) 122456
(B) 220020
(C) 220022
(D) 235467
(E) 220026
A: OK... Stream of consciousness: (555 + 445) * 2 * 110 + 20 = 220000 + 20 = 220020
The answer is (B).

Q: A 600 meter long train crosses a signal post in 40 seconds. How long will it take to cross a 3 kilometer long bridge, at the same speed?
Options:
(A) 4
(B) 5
(C) 6
(D) 7
(E) 8
A: OK... Stream of consciousness: S = 600/40 = 15 mps
S = 3600/15 = 240 sec = 4 min
The answer is (A).

Q: For integers U and V, when U is divided by V, the remainder is odd. Which of the following must be true?
Options:
(A) At least one of U and V is odd
(B) The sum U + V is odd
(C) U and V share no common factors other than 1
(D) UV is odd.
(E) U is odd
A:
OK... Stream of consciousness: At least one of U and V is odd
The answer is (A).