Car is traveling

A car is traveling at a uniform speed.The driver sees a milestone showing a 2-digit number. After traveling for an hour the driver sees another milestone with the same digits in reverse order.After another hour the driver sees another milestone containing the same two digits. What is the average speed of the driver?

Ans

45 kmph

Father's age

Father's age is three years more than three times the son's age.After three years, father's age will be ten years more than twice the son's age. What is the father's present age?


Ans:
33 years.

Array of size

Given an array of size n+1 which contains all the numbers from 1 to n. Find the number which is repeated in O(n) time. How do you proceed with the same with floating numbers from 0 to 1 instead of 1 to n?

Ans

The number appearing 2 times is (sum of all the numbers in the array) - (sum of the numbers from 1 to n). For floating numbers multiply it with 100 and proceed.

Two trains enter at the opposite

Two trains enter at the opposite sides of a tunnel of length L with speeds 'V'. A particle enters the tunnel at the same time with a speed 'v' and it vibrates in the tunnel[i.e. if it reaches the end of the tunnel then it comes back]. What is the position of the particle by the time the 2 trains meet?

Ans

If v<=2V then the position is (v*L)/(2*V) from the starting point else it is 2*L -(v*L)/(2*V) from the starting point.

Missing number

Given an array of size n. It contains numbers in the range 1 to n. Each number is present at least once except for 1 number. Find the missing number.

Array of size n

Given an array of size n, containing every element from 1 to n+1, except one. Find the missing element.

N red balls

Given n red balls and m blue balls and some containers, how would you distribute those balls among the containers such that the probability of picking a red ball is maximized, assuming that the user randomly chooses a container and then randomly picks a ball from that.

Given a cube of size n*n*n (i.e made up of n^3 smaller cubes), find the number of smaller cubes on the surface. Extend this to k-dimension.

Given an array of size n. It contains numbers in the range 1 to n. Find the numbers which aren’t present.

Given an array of size n. It contains numbers in the range 1 to n. Each number is present at least once except for 2 numbers. Find the missing numbers.