London School of Hygiene and Tropical Medicine 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: 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: 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 two balls touching each other circumferencically. The radius of the big ball is 4 times the diameter of the small all. The outer small ball rotates in anticlockwise direction circumferencically over the bigger one at the rate of 16 rev/sec. The bigger wheel also rotates anticlockwise at N rev/sec. What is 'N' for the horizontal line from the centre of small wheel always is horizontal.

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: 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: A light bulb is hanging in a room. Outside of the room there are three switches, of which only one is connected to the lamp. In the starting situation, all switches are 'off' and the bulb is not lit. If it is allowed to check in the room only once.How would you know which is the switch?

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: 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: The egg vendor calls on his first customer and sells half his eggs and half an egg. To the second customer, he sells half of what he had left and half an egg and to the third customer he sells half of what he had then left and half an egg. By the way he did not break any eggs. In the end three eggs were remaining . How many total eggs he was having ?

Q: Every day a cyclist meets a train at a particular crossing .The road is straight before the crossing and both are travelling in the same direction.Cyclist travels with a speed of 10 kmph.One day the cyclist come late by 25 minutes and meets the train 5 km before the crossing.What is the speed of the train?

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: 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: 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: 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 family X went for a vacation. Unfortunately it rained for 13 days when they were there. But whenever it rained in the mornings, they had clear afternoons and vice versa. In all they enjoyed 11 mornings and 12 afternoons. How many days did they stay there totally?

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: Motorboat A leaves shore P as B leaves Q; they move across the lake at a constant speed. They meet first time 600 yards from P. Each returns from the opposite shore without halting, and they meet 200 yards from. How long is the lake?

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: 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"