q: There are five same model cars parked in the same direction in parking. If 3 cars are red, 1 is black and 1 is green, in how many ways they can be arranged in the parking?
Options:
(A) 10 ways.
(B) 20 ways.
(C) 30 ways.
(D) 40 ways.
(E) 50 ways.
a: Stream of consciousness: 5!/(3!*1!*1!) = (5*4*3*2*1)/(3*2*1) = 120/6 = 20 ways. The answer is (B).

question: The speed of a car is 80 km in the first hour and 60 km in the second hour. What is the average speed of the car?
Options:
(A) 50 kmph
(B) 60 kmph
(C) 70 kmph
(D) 80 kmph
(E) 85 kmph
answer: Stream of consciousness: S = (80 + 60)/2 = 70 kmph The answer is (C).

q: A train running at the speed of 142 km/hr crosses a pole in 12 seconds. Find the length of the train.
Options:
(A) 540
(B) 288
(C) 200
(D) 340
(E) 712
a: Stream of consciousness: Speed = 162*(5/18) m/sec = 45m/sec
Length of Train (Distance) = Speed * Time
45 * 12 = 540 meter The answer is (A).

question: 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
answer: 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: The average of 13 numbers is 60. Average of the first 7 of them is 57 and that of the last 7 is 61. Find the 8th number?
Options:
(A) 46
(B) 77
(C) 88
(D) 544
(E) 33
a: Stream of consciousness: Sum of all the 13 numbers = 13 * 60 = 780
Sum of the first 7 of them = 7 * 57 = 399
Sum of the last 7 of them = 7 * 61 = 427
So, the 8th number = 427 + 399 - 780 = 46. The answer is (A).

q: If the average (arithmetic mean) of the four numbers K, 2K + 3, 3K 5 and 5K + 1 is 41, what is the value of K?
Options:
(A) 41
(B) 15 3/4
(C) 22
(D) 23
(E) 25 3/10
a:
Stream of consciousness: K + 2K +3 + 3K - 5 + 5K +1 = 11K -1
(11K -1)/4 = 41
11K = 41 * 4 +1 = 164 +1 = 165
K = 165 / 11 = 15. The answer is (A).