Posted by **alya** on Wednesday, September 28, 2011 at 8:52am.

you have 6 iron balls. 5 iron balls have equal weight and 1 iron ball is slightly lighter than the other 5 iron balls. you are given a libra. find ways (most minimum) to find out the light.

- PROBLEM SOLVING IN MATHEMATICS -
**Reiny**, Wednesday, September 28, 2011 at 9:06am
typically in this type of question, you can only use a "fair balance"

1st weighing:

place 3 balls on each side of the balance, that will tell you which set of 3 contains the lighter ball

2nd weighing:

place a ball on each side of the balance, keep the third back in your hand.

a) If they balance, the the ball in your hand is the lightest

b) If the balls don't balance, it will show which is the lightest.

2 weighings are necessary.

- PROBLEM SOLVING IN MATHEMATICS -
**Reiny**, Wednesday, September 28, 2011 at 9:08am
should have said:

2nd weighing:

From the set of balls with the lighter ball, place a ball on each side of the balance, keep the third back in your hand.

etc

## Answer This Question

## Related Questions

- MTH 156 - The ratio of the distances a 7-iron and a 5-iron will drive a golf ...
- math - the ratio of the distances a 7-iron and a 5- iron will dirve a golf ball ...
- Physics - What is the gravitational force between two 10 kg iron balls separated...
- Basic Mathematics - A bag contains 2 red balls, 3 blue balls and 5 green balls. ...
- math - Write the numbers in order of increasing size. 1/2,3/4,2/3,0.95 Convert ...
- Chemistry - Iron ores have different amounts of iron per kilogram of ore. ...
- Chemistry - I looked and could not find anything on iron smelting? Could you ...
- Chemistry - The specfic heat of iron is 0.11cal/g C. The heat of fusion of iron...
- Math - A bag contains 5 balls,8 white balls, 9 green balls,7 blue balls& 6 ...
- Physical Science 2 - Given that iron has a density of 7.87 g/cm3, calculate the ...

More Related Questions