hack reactor Recruitment Process, Interview Questions & Answers

Q: In a sports contest there were m medals awarded on n successive days (n > 1). 1. On the first day 1 medal and 1/7 of the remaining m - 1 medals were awarded. 2. On the second day 2 medals and 1/7 of the now remaining medals was awarded; and so on.On the nth and last day, the remaining n medals were awarded.How many days did the contest last, and how many medals were awarded altogether?

Q: A rich merchant had collected many gold coins. He did not want anybody to know about them. One day his wife asked, "How many gold coins do we have?" After pausing a moment, he replied, "Well! If I divide the coins into two unequal numbers, then 32 times the difference between the two numbers equals the difference between the squares of the two numbers."The wife looked puzzled. Can you help the merchant's wife by finding out how many gold coins they have?

Q: Suppose a newly-born pair of rabbits, one male, one female, are put in a field. Rabbits are able to mate at the age of one month so that at the end of its second month a female can produce another pair of rabbits. Suppose that our rabbits never die and that the female always produces one new pair (one male, one female) every month from the second month on.

Q: 9 cards are there. You have to arrange them in a 3*3 matrix. Cards are of 4 colors. They are red, yellow, blue and green. Conditions for arrangement: one red card must be in first row or second row. 2 green cards should be in 3rd column. Yellow cards must be in the 3 corners only. Two blue cards must be in the 2nd row. At least one green card in each row.

Q: The citizens of planet nigiet are 8 fingered and have thus developed their decimal system in base 8. A certain street in nigiet contains 1000 (in base 8) buildings numbered 1 to 1000. How many 3s are used in numbering these buildings?

Q: At 6?o a clock ticks 6 times.The time between first and last ticks is 30 seconds.How long does it tick at 12?o clock?2.A hotel has 10 storey. Which floor is above the floor below the floor, below the floor above the floor, below the floor above the fifth.

Q: There is a room with a door (closed) and three light bulbs. Outside the room there are three switches, connected to the bulbs. You may manipulate the switches as you wish, but once you open the door you can't change them. Identify each switch with its bulb.

Q: There are 7 letters A,B,C,D,E,F,GAll are assigned some numbers from 1,2 to 7.B is in the middle if arranged as per the numbers.A is greater than G same as F is less than C.G comes earlier than E.Which is the fourth letter

Q: In a Park, N persons stand on the circumference of a circle at distinct points. Each possible pair of persons, not standing next to each other, sings a two-minute song ? one pair immediately after the other. If the total time taken for singing is 28 minutes, what is N?

Q: Give two dice - one is a standard dice, the other is blank (nothing painted on any of the faces). The problem is to paint the blank dice in such a manner so that when you roll both of them together, the sum of both the faces should lie between 1 and 12. Numbers from 1-12 (both inclusive) equally likely.

Q: Raj has a jewel chest containing Rings, Pins and Ear-rings. The chest contains 26 pieces. Raj has 2 and 1/2 times as many rings as pins, and the number of pairs of earrings is 4 less than the number of rings. How many earrings does Raj have?...

Q: If I walk with 30 miles/hr i reach 1 hour before and if i walk with 20 miles/hr i reach 1 hour late. Find the distance between 2 points and the exact time of reaching destination is 11 am then find the speed with which it walks.

Q: There are four dogs/ants/people at four corners of a square of unit distance. At the same instant all of them start running with unit speed towards the person on their clockwise direction and will always run towards that target. How long does it take for them to meet and where?

Q: Given a collection of points P in the plane , a 1-set is a point in P that can be separated from the rest by a line, .i.e the point lies on one side of the line while the others lie on the other side. The number of 1-sets of P is denoted by n1(P)....

Q: Jack and his wife went to a party where four other married couples were present. Every person shook hands with everyone he or she was not acquainted with. When the handshaking was over, Jack asked everyone, including his own wife, how many hands they shook?

Q: In a country where everyone wants a boy, each family continues having babies till they have a boy. After some time, what is the proportion of boys to girls in the country? (Assuming probability of having a boy or a girl is the same)

Q: An escalator is descending at constant speed. A walks down and takes 50 steps to reach the bottom. B runs down and takes 90 steps in the same time as A takes 10 steps. How many steps are visible when the escalator is not operating. 

Q: A Man is sitting in the last coach of train could not find a seat, so he starts walking to the front coach ,he walks for 5 min and reaches front coach. Not finding a seat he walks back to last coach and when he reaches there,train had completed 5 miles. what is the speed of the train ?

Q: A man driving the car at twice the speed of auto one day he was driven car for 10 min. and car is failed. he left the car and took auto to go to the office .he spent 30 min. in the auto. what will be the time take by car to go office?

Q: A person meets a train at a railway station coming daily at a particular time. One day he is late by 25 minutes, and he meets the train 5 k.m. before the station. If his speed is 12 kmph, what is the speed of the train.