Reasoning: D = 90 * 5/18 * 5 = 125 m
Ans: (A)
Question: If a train, travelling at a speed of 90 kmph, crosses a pole in 5 sec, then the length of train is?
Options:
(A) 125 m
(B) 104 m
(C) 140 m
(D) 152 m
(E) 150 m
Rationale: Total number of ways = 9!*2!.
The answer: (A)
Question: There are 12 person among whom 2 are brother. The total no.of ways in which these persons can be seated around a round table so that exactly 1 person sit between the brothers, is equal to?
Options:
(A) 9!*2!
(B) 7!*2!
(C) 6!*1!
(D) 2!*1!
(E) 5!*1!
Reasoning: T = 65/32 * 18/5 = 7 sec
Ans: (E)
Question: In what time will a railway train 65 m long moving at the rate of 32 kmph pass a telegraph post on its way?
Options:
(A) 3 sec
(B) 4 sec
(C) 5 sec
(D) 6 sec
(E) 7 sec
Rationale: Correct Answer: (E)
Let's go through each answer choice: (A) can never be true, since no negative is greater than a positive. (B) doesn't have to be true consider what would happen if x = -2 and y = 1. (C) can never be true, as x^3 must be negative, and y^2 must be positive. (D) can never be true, since if x < 0, -x is the same thing as |x|, and |x| > y. (E) can be manipulated by multiplying both sides by -1, which gives us x > y. Remember that x < 0, so x = |x|, and y is positive, so |y| = y. Thus x < y is the same statement as |x| > |y|, and (D) must be true.
The answer: (D)
Question: If x<0, y>0, and |x| < |y|, which of the following must be true?
Options:
(A) x > y
(B) y^2 > x^2
(C) x^3 > y^2
(D) x < y
(E) x < y
Reasoning: Total age of students is 32X16 = 512 Years
Total age inclusive of teacher = 33X (16+1) = 561
So, Teacher's age is 561-512 = 49 Yrs
There is a shortcut for these type of problems
Teacher's age is 16+(33X1) = 49 Years
Ans: (E)
Question: The average age of a class of 32 students is 16 yrs. if the teacher's age is also included, the average increases by one year. Find the age of the teacher
Options:
(A) 30 Years
(B) 31 Years
(C) 32 Years
(D) 34 Years
(E) 49 Years
Reasoning: Length of the train be 'X'
X + 150/15 = X + 250/20
4X + 600 = 3X + 750
X = 150m ]
Ans: (A)
Question: A train crosses a platform of 150 m in 15 sec, same train crosses another platform of length 250 m in 20 sec. then find the length of the train?
Options:
(A) 150
(B) 78
(C) 268
(D) 268
(E) 298