There are 9 baskets with pebbles in it.Every basket have pebbles weighing 1gm except one which has pebbles weighing 2gm.There is a weighing machine. Use the weighing machine only once and find which basket have pebbles that weigh 2gm? Answers: A) 9th B) 8th C) 6th D) 4th E) 5th
Take 1 pebble form 1st basket, 2 from 2nd, 3 from 3rd,...9 from the 9th basket and weigh them. If all the baskets contained 1gm pebbles the weight would have been 45 [ 1+2+3+..9 = 45]   Since 1 of the basket contains 2 gm pebbles the weight will be more than 45.   Subtract 45 from the weight to get the basket number.   ie   if the weight is 49   49 - 45= 
<gadget id="calculator">49 - 45</gadget>
<output>4</output>
4   4th basket   ANSWER:4th
<result>D</result>
There are 9 baskets with pebbles in it.Every basket have pebbles weighing 1gm except one which has pebbles weighing 2gm.There is a weighing machine. Use the weighing machine only once and find which basket have pebbles that weigh 2gm?