Saturday, 22 October 2011

Arithmetic-7 (Placement Q's) (GMAT/GRE word problem)

Potatoes are made up of 99% water and 1% "potato matter." Jack bought 100 pounds of potatoes and left them outside in the sun for a while. When he returned, he discovered that the potatoes had dehydrated and were now only made up of 98% water. How much did the potatoes now weigh?
(A) 98 pounds
(B) 99 pounds
(C) 90 pounds
(D) 50 pounds 
Solution follows here:

Initially, weight of water 99% and of potato-content is 1%
ð Out of a total weight of 100 pounds, weight of water is 99 pounds and weight of potato-content is 1 pound.
After dehydration, let the total weight be ‘x’.

Total weight
Weight of water
Weight of “potato content”
After Dehydration
0.98 * x
0.02 * x

Key point to be noted here is:
“After dehydration, weight of potato content does not change”
0.02 * x = 1
x = 1/0.02 = 100/2 = 50
Answer is (D)

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