DRDO BU Center For Life Sciences Recruitment Process, Interview Questions & Answers

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: A rich man died. In his will, he has divided his gold coins among his 5 sons, 5 daughters and a manager. According to his will: First give one coin to manager. 1/5th of the remaining to the elder son.Now give one coin to the manager and 1/5th of the remaining to second son and so on..... After giving coins to 5th son, divided the remaining coins among five daughters equally.All should get full coins. Find the minimum number of coins he has?

Q: Consider a pile of Diamonds on a table. A thief enters and steals 1/2 of the total quantity and then again 2 extra from the remaining. After some time a second thief enters and steals 1/2 of the remaining+2. Then 3rd thief enters and steals 1/2 of the remaining+2. Then 4th thief enters and steals 1/2 of the remaining+2. When the 5th one enters he finds 1 diamond on the table. Find out the total no. of diamonds originally on the table before the 1st thief entered.

Q: There are 3 clans in an island - The Arcs who never lie, the Dons who always lie and the Slons who lie alternately with the truth. Once a tourist meets 2 guides who stress that the other is a Slon. They proceed on a tour and see a sports meet. The first guide says that the prizes have been won in the order Don, Arc, Slon. The other says that, the order is Slon, Don, Arc. (the order need not be exact). To which clan did each of the guides and the players belong? ...

Q: 36 people {a1, a2, ..., a36} meet and shake hands in a circular fashion. In other words, there are totally 36 handshakes involving the pairs, {a1, a2}, {a2, a3}, ..., {a35, a36}, {a36, a1}. Then size of the smallest set of people such that the res...

Q: There are 3 sticks placed at right angles to each other and a sphere is placed between the sticks . Now another sphere is placed in the gap between the sticks and Larger sphere . Find the radius of smaller sphere in terms of radius of larger sphere.

Q: A vessel is full of liquid. From the vessel, 1/3rd of the liquid evaporates on the first day. On the second day 3/4th of the remaining liquid evaporates. What fraction of the volume is present at the end of the second day

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: 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: 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 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.

Q: There are some chickens in a poultry. They are fed with corn. One sack of corn will come for 9 days. The farmer decides to sell some chickens and wanted to hold 12 chicken with him. He cuts the feed by 10% and sack of corn comes for 30...

Q: In mathematics country 1,2,3,4....,8,9 are nine cities. Cities which form a no. that is divisible by 3 are connected by air planes. (e.g. cities 1 & 2 form no. 12 which divisible by 3 then 1 is connected to city 2). Find the total no. of ways you can go to 8 if you are allowed to break the journeys.

Q: Four persons have to cross the bridge they are having one torch light. Four persons take 1,2,5,10 minutes respectively, when two persons are going they will take the time of the slowest person. What is the time taken to cross by all of them.

Q: The profit made by a company in one year is enough to give 6% return on all shares. But as the preferred shares get on return of 7.5%, so the ordinary shares got on return of 5%. If the value of preferred shares is Rs 4,000000, then what is the va...

Q: On a particular day A and B decide that they would either speak the truth or will lie. C asks A whether he is speaking truth or lying? He answers and B listens to what he said. C then asks B what A has said B says "A says that he is a liar"

Q: There are 4 cars . They all are coming from different directions. They have to cross through one square.They all arrive at the same time. Nobody stops . still there is no clash .note : They all are driving at a speed if 100 km/hr.