Set III

11.	You have 9 rings alike. But in those 9, only one is lighter than the rest. In how many times we could find the lighter one by using the weight?

Answer & Explanation

Explanation :

1st attempt:
You need to weigh 3 rings along with another 3 rings. If they are equal, then the remaining 3 will contain that lighter one.
If in that comparison one side is up and another is down, then the 3 rings in upper side will contain the lighter one. Since upper indicates light weight.
2nd attempt:
Take two rings from those three which contains lighter one. Now place one ring in each side. If both sides are equal the un-weighed one is lighter.
If one side is up and another is down, it means that the ring in upper side will be the lighter one. 
So we need only 2 attempts to find the lighter ring.

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12.	In a room 6 chairs are arranged one above the other. 3 persons with 25 years of age and 3 with 45 years of age are coming for that room. How many chairs need to be taken from them to make all of them to be seated?

Answer & Explanation

Explanation :

Answer: 5 chairs
If we take 5 chairs then 1 chair will be on the floor already. So we need to take only 5 chairs which are above the bottom most chair.

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13.	In a city there were pillars in straight line. In between each pillar there was 10 meters gap. Then how far will the 12th pillar be from the first pillar?

Answer & Explanation

Explanation :

Answer: 110 meter
There will be only 11 gaps between 12 pillars. So there will be 11 x 10 = 110 meter in between them. 

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14.	If 7 goats take 7 days to eat 7 bundle of grasses. How much time will a goat take to eat 1 bundle of grass?

Answer & Explanation

Explanation :

Answer: 7 days

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