Fresh grapes contain 90% by weight while dried grapes

Question

Fresh grapes contain 90% by weight while dried grapes contain 20% water by weight. What is the weight of dry grapes available from 20 kg of fresh grapes?

A. 2 kg
B. 2.4 kg
C. 2.5 kg
D. 10 kg
E. none of these

Bunuel · Accepted Answer

The weight of non-water in 20 kg of fresh grapes (which is 100-90=10% of whole weight) will be the same as the weight of non-water in x kg of dried grapes (which is 100-20=80% of whole weight), so  20*0.1=x*0.8  -->  x=2.5 .

Answer: C.

GoAlexis · Answer

From the question we know: 20kg * 90% = 18kg of water in the fresh grapes

20kg - 18kg of water = 2kg of non-water mass

We are looking for the weight of the dry grapes (X).

Since the question tells us that 20% of the weight of the dry graps is water and we know that 2kg is non-water mass we can set up the following equation:

X = 1/5(X) + 2kg
4/5(X) = 2kg
X = 5/2 or 2.5 kg

I hope that helps!

feruz77 · Answer

Here is an official explanation how to solve this problem:

Let x kg dry grapes be obtained. Then, solid part in fresh grapes = solid part in dry grapes
0.1*20=0.8x*x
x=2,5

I do not find this explanation an approriate one because something must be wrong with 0.8x*x.

Can somebody suggest an alternative way of solution?
Thanks. My appreciations+KUDOS!!!

stne · Answer

another attempt to make this question easier to understand

question is asking what amount of dry grapes will yield mass of 2 kg

or 
80 % of what = 2 kg
 
answer 2.5

Muzamil94 · Answer

10% of 20 kg = 2kg is without water, there is no water at all in these 2 kg but we need weight with 20% of water and 80% without water. Let X be the weight with 20% water. Therefore X will have the same 2 kg without water, that means these 2kg will be 80% of X, therefore:

80% of X = 2kg
=> X = 2.5kg

Posted from my mobile device

80% of X = 2kg
=> X = 2.5kg

Posted from my mobile device

Harman95 · Answer

Since the grape content will remain the same
For 20 Kg fresh water grapes if water=90%, grape content= 10%
so 10% of 20= 2 Kg
So in the dry grape, grape content = 2kg
Here water: grape content= 20:80= 1:4 so for 2 kg grape content, water= 0.5: 2
Hence total weight= 2.5 Kg

DiwakarDC · Answer

Since,
Dry grapes+Water = Fresh grapes
One can also do this problem by alligating water.
DRY GRAPES(water)______WATER
________20_________________100
________'________90_________'
________10_________________70
 Ratio=> 10 : 70 = 1:7 
The weight of Dry grapes
 = 1/8×20 = 2.5kgs

I hope this method will help to solve such questions quickly.

Thank you!

Posted from my mobile device

shivangibh · Answer

Please find solution in the attached image.

srm91 · Answer

20 kg fresh grapes contains 18 kg (90%) water and remaining 2 kg (20-18 kg) pulp.

When grapes is dried, pulp content remains same (2 kg), whereas water gets dried to lets say x kg.

x kg is 20 % of the entire weight (x+2) kg {water + pulp content}

Therefore, x=0.2(x+2). Hence x=0.5 kg.

Weight of dried grapes = 2 kg (pulp) + 0.5 kg (water) = 2.5 Kg

CrackverbalGMAT · Answer

Fresh grapes contain 90% by weight while dried grapes contain 20% water by weight. What is the weight of dry grapes available from 20 kg of fresh grapes?

It's given that fresh grapes contain 90% water by weight , that means non-water content in fresh grapes will be 10% by weight.
Similarly, dried grapes contain 20% water by weight, so we can also say that non-water content in dried grapes will be 80% by weight.

Here we need to find the weight of dry grapes available from 20 kg of fresh grapes.

Assume that weight of dried grapes available would be X.

So, the non- water content of 20 kg of fresh grapes will be equal to non-water content of X kg of dried grapes available from that.

10% of 20 = 80 % of X

X= 10* 20 / 80 = 20/8 = 2.5 kg

Option C is the answer.

Thanks,
  Clifin J Francis,
GMAT SME

sujoykrdatta · Answer

Pulp from fresh grapes = 10% of 20 = 2 kg
Pulp from dried grapes = 80% of x = 0.8x kg
Thus: 0.8x = 2 
=> x = 2.5 kg

Answer C

luisdicampo · Answer

Deconstructing the Question

Fresh grapes contain  90% water , so solids are  10% .

Dried grapes contain  20% water , so solids are  80% .

The amount of solids remains constant.

Step-by-step

Fresh grapes =  20 kg

Solids initially:

0.10 	imes 20 = 2

Let final weight be  W .

Since solids are 80% in dried grapes:

0.80W = 2

W = \frac{2}{0.80} = 2.5

Answer: C

Fresh grapes contain 90% by weight while dried grapes

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

Fresh grapes contain 90% by weight while dried grapes

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards