There are 10 cig packs each containing an unknown no of cigs( each = Pack has between 50 and 100). One pack has all bad cigs . Each good cig = ( if u can agree that any cig is good) weighs 1gm. Each bad cig weighs = 1.1 gm or .99 gm but all bad cigs weigh same. Using a spring chemical = Balance ( which gives u the exact weight) .find out which pack is bad ,Using the balance only once.
Asked by Pritha sharma
balakrishnan   anyone knows ans fr dis...
6 years ago
Lucy Desouza   Take 1 cig from Pack 1, 2 cig from pack 2, 3 cig from pack 3, 4 cig from pack 4, 5 cig from pack 5, .. .. . 10 cig from pack 10.Then If all are gud..Total weight of cig will be 1 +2 + 3
+ .. .10 = 55 gm
If Defective is in pack 1.Then sum will be 54.9 or 55.1
If Defective is in pack 2.Then sum will be 54.8 or 55.2
If Defective is in pack 3.Then sum will be 54.7 or 55.3
........................................ ........................................ ..
Like this we can find out :) Which pack is bad :) Any queries regarding explanation comment :)
6 years ago
sangram   i think solution is not possible
5 years ago
RAJ SUDHEE ZEMECKIS   @lucy :what if he has taken two cigars from pack 2 one is 1.1 gm and another is 0.9gm . total becomes 55;
from pack 4:if we take two &two like 2*1.1+2*0.9=55;
it happens for all even numbered packs , how to find the defective cig pack in this case ???

can u give me solution for this scenario ?
5 years ago
Lucy Desouza   @Raj Sudheer Read the question properly..Each bad cig weighs = 1.1 gm or .99 gm but all bad cigs weigh same.
One pack has all bad cigs ...Your case is not possible becuase either its 1.1 or .99 but not both. :)
5 years ago
Vaibhav Patel   question is very simple
we have to use chemical balance.
first you have to assume one thing that bad cig is light or heavy than good one.here i choose bad one are light
then first pick 2 pack and put it on balance and check any difference....if you see then the uplifted pack of cig is bad one.
if not then go for 8 pack......4 one side and 4 another side....
not you will get another 4 including bad one
now try for 4(2+2 both side)
then try for 2(1+1 both side)
now you will get the bad pack
3 years ago

Smiley