There are 9 coins. Out of which one is odd one i.e weight
is less or more. How many iterations of weighing are
required to find odd coin?

Answer Posted / shashank parulekar

There are 9 coins. Out of which one is odd one i.e. weight
is less or more. How many iterations of weighing are
required to find odd coin?

Divide the coins into 3 groups of 3 each
1. Weigh the first two (Iteration 1)
a. If they are of equal weight, the third group is defective.
i. Weigh two of the third group. (Iteration 2)
1. If they are of equal weight, the third is defective. Weigh it with a normal coin from the first group (Iteration 3). It weighs less or more. That is the final answer.
2. If they are of unequal weight, weigh the heavier one with a normal one in the first group (Iteration 3). If it is heavier, it is the defective one, weighing more than the rest. If it weighs the same as the normal one, the second coin is the defective one, weighing less than the others.
b. If they are of unequal weight, one of them is defective and the third group is normal. Weigh the first of the groups with the third group (Iteration 2). If they weigh equal, the second group is defective. If they do not weigh equal, the first group is defective. The defective group could weigh less or more than normal, depending on whether the defective coin weighs less or more.
i. Weigh coin one and two from the defective group (Iteration 3). If they weigh equal, the third coin is defective.
ii. If they do not weigh equal,
1. the coin that weighs more is defective if the group was defective-heavy.
2. the coin that weighs less is defective if the group was defective-lighter.

Is This Answer Correct ?    5 Yes 4 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

one question has last part like difference between two terms is 9 and product of two numbers is 10, what is the squares of sum of numbers?

774


A bike runs at the speed of 50 km/h when not serviced and runs at 60 km/h when serviced. After servicing the bike covers a certain distance in 6 h. How much time will the car take to cover the same direction?

790


If a bat costs Rs.30 in the year 1999 and Rs.250 in the year 2000.What is the percent increase in price?

804


25 stations ,24 stations are inbetween- - - - - how many tickets should be required.

674


The average of the first 100 positive integers is?

709






Total balls z,red balls N remaining are blak balls,then %of black balls equal to

700


Hello My name is vijay right now I'm preparing for SBI po, I am good at aptitude but not better. I am lagging time you know competitive exams are to answer in span of time. So any website regarding aptitude short cuts or tricks Pls post to my mail. I am waiting

1594


2 persons can finish a job in 8 days. First person alone can finish the work in 24 days. How many days does the second person take to finish the job?

1099


There are 6 people W,H,M,C,G,F who are murderer, victim, judge, police, witness, hangman. There was no eyewitness only circumstantial witness. The murderer was sentenced to death. Read following statement and determine who is who.

704


'X' liters of petrol can be filled in an automobiles tank. What part of full tank was removed, if 'Y' liters was removed when the tank was full?

697


A boy picks up the phone and asks" who are you?" The voice from the other side answers" I am your mother's mother in law".What is the relation of the boy with the fellow speaking at the other end.

833


What are the areas shell do ask questions during their technical selection test? send it to my email: kingsbogon@yahoo.com ,Thank you in advance

1595


What percent of 60 is 12?

807


In a show, ticket numbers from 101 to 350 are made to sit consecutively. What is the probability that the number of the ticket, selected at random, will be a hundredth digit of 2?

793


A cycled from P to Q at 10 kmph and returned at the rate of 9 kmph. B cycled both ways at 12 kmph. In the whole journey B took 10 minutes less than A. Find the distance between P and Q.

822