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:

Solution:

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”
Initially	100	99	1
After Dehydration	x	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)