q: If X is the sum of first 30 positive even integers and Y is the sum of first 30 positive odd integers, what is the value of x-y?
Please try to explain your answers
Options:
(A) 10
(B) 25
(C) 30
(D) 75
(E) 100
a: 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 30 positive even integers minus the sum of first 30 positive odd integers will be 30. The answer is (C).

question: A train 280 m long, running with a speed of 63 km/hr will pass a tree in?
Options:
(A) 22 sec
(B) 16 sec
(C) 17 sec
(D) 88 sec
(E) 12 sec
answer: Stream of consciousness: Speed = 63 * 5/18 = 35/2 m/sec
Time taken = 280 * 2/35 = 16 sec The answer is (B).

q: A and B together can do a work in 6 days. If A alone can do it in 15 days. In how many days can B alone do it?
Options:
(A) 7
(B) 13
(C) 19
(D) 10
(E) None
a: Stream of consciousness: 1/6 1/15 = 1/10
B can do the work in 10 days The answer is (D).

question: In how many different ways can the letters of the word 'DIVIDED' be arranged?
Options:
(A) 250
(B) 280
(C) 300
(D) 420
(E) 360
answer: Stream of consciousness: Number of ways = 7!/3!2! = 7X6X5X4X3X2X1/3X2X1X2X1 = 420 The answer is (D).

q: A light has a rating of 110 watts, it is replaced with a new light that has 30% higher wattage. How many watts does the new light have?
Options:
(A) 143
(B) 145
(C) 156
(D) 134
(E) 100
a: Stream of consciousness: Final number = Initial number + 30%(original number) = 110 + 30%(110) = 110 + 33 = 143. The answer is (A).

q: If the cost price of 50 articles is equal to the selling price of 15 articles, then the gain or loss percent is?
Options:
(A) 16
(B) 127
(C) 12
(D) 18
(E) 233
a:
Stream of consciousness: Percentage of profit = 35/15 * 100 = 233% The answer is (E).