Rationale: Total age of students is 42X16 = 672 Years
Total age inclusive of teacher = 43X (16+1) = 731
So, Teacher's age is 731-672 = 59 Yrs
There is a shortcut for these type of problems
Teacher's age is 16+(43X1) = 59 Years
The answer: (E)
Question: The average age of a class of 42 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) 59 Years

Rationale: Area of a parallelogram = base * height = 24 * 16 = 384 cm2
The answer: (A)
Question: Find the area of a parallelogram with base 24 cm and height 16 cm.
Options:
(A) 384 cm^2
(B) 200 cm^2
(C) 250 cm^2
(D) 350 cm^2
(E) 400 cm^2

Rationale: Speed = 45 * 5/18 = 25/2 m/sec
Total distance covered = 310 + 140 = 450 m
Required time = 450 * 2/25 = 36 sec
The answer: (D)
Question: A train 310 m long is running at a speed of 45 km/hr. In what time will it pass a bridge 140 m long?
Options:
(A) 40 sec
(B) 50 sec
(C) 44 sec
(D) 36 sec
(E) 60 sec