A large urn contains 100 balls, of which 36% are red and the rest are

Question

A large urn contains 100 balls, of which 36% are red and the rest are blue. How many of the blue balls must be removed so that the percentage of red balls in the urn will be 72% (No red balls are to be removed.)
A) 28
B) 32
C) 36
D) 50
E) 64

chetan2u · Answer

Now 36% are red means 36 are red and 100-36 or 64 are blue.

Some blue balls are removed and 36 has now become 72%.
Let the final number after removal is y..
So  \frac{72}{100} y=36.....y=36*100/72=50
So the total number of balls left is 50, which means 100-50 or 50 have been removed.
As we know only blue balls have been removed, 50 blue balls must be removed..

D

Archit3110 · Answer

This took me ~2 mins to understand the question ..

From given info total balls =100, out of which red 36 and blue 64

We have to find total of balls which would make the count of 36 red balls as 72% of the total which has to be done by removal of blue balls.

So lets find value of total balls at which 36 red balls is 72%
Let x be total balls
36/x= 0.72
solve of x we get 50 , since given that total balls are 100 and we have found that @ 50 , 36 red balls would be 72% so we would have to remove 50 out of 64 available blue balls to make the red balls @ 72%, IMO D..

NCRanjan · Answer

36
______ X 100 = 72 ( Removing X Blue balls from total 100 balls )
100-X

Solving for x value is 50

dollytaneja51 · Answer

(36/100-X)*100 = 72
3600=7200-72X
3600 = 72X
50 = X

50 blue balls need to be removed.

D is the correct answer

luisdicampo · Answer

Deconstructing the Question

Initial state:  100 balls total.  36 Red  (36%) and  64 Blue  (64%). 
  Action:  Remove only Blue balls. 
  Goal:  Red balls (which stay at 36) must represent  72%  of the new total.

Step 1: Calculate the New Total (T)  
Since the number of Red balls is constant:
 72\% * T = 36 
 0.72 * T = 36 
 T = 36 / 0.72 
 T = 3600 / 72 =    50

The new total number of balls in the urn must be  50 .

Step 2: Calculate Balls Removed  
 Number to remove = Initial Total - New Total 
 Removed = 100 - 50 =    50

The correct answer is D.

A large urn contains 100 balls, of which 36% are red and the rest are

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A large urn contains 100 balls, of which 36% are red and the rest are

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