A watermelon composed of 99% of water, weighted 10kg.
After a while, some of water evaporated, leaving the watermelon composed of 98% of water. What is the new weight of water-melon?

Question

A watermelon composed of 99% of water, weighted 10kg.
After a while, some of water evaporated, leaving the watermelon composed of 98% of water. What is the new weight of water-melon?

anonymous · Answer

is      %
-   x  -
of      100

anonymous · Answer

then cross multiply

anonymous · Answer

sup homies the answer is

anonymous · Answer

99% OF 10kg ....

anonymous · Answer

This is a tricky question...

anonymous · Answer

x        99
-   x   -
10     100

anonymous · Answer

Would that mean- 
100x=990?

anonymous · Answer

yea then divide

anonymous · Answer

9.9?

espex · Answer

While rounded the answers are the same, I would offer a slight modification from @mads4566 approach. Use the ratio of water to weight as:
$$\frac{.99}{10} = \frac{.98}{x}$$
And cross multiply as suggested.

anonymous · Answer

Thanks @eSpeX

espex · Answer

You're welcome, @mads4566 got the ball rolling too. :)

anonymous · Answer

ahah yeah (: Thank you BOTH

anonymous · Answer

a cute question can also solve like this
if the ten pounds of  watermelon starts at 99% water, then you have 9.9 pounds of water and .1 pound of solid
then some water evaporates, but you still have .1 pound of solid, which is 2% of the total
solve 2% of what number is .1 via $.1\div .02$ do get the answer

anonymous · Answer

Sorry but im confused now...

anonymous · Answer

i am not sure what the first answers above give, but it looks like they give the wrong answer 

$$\frac{.1}{.02}=\frac{10}{2}=5$$  so the weight is 5 pounds

anonymous · Answer

it is a tricky question, so lets go slow

espex · Answer

Are you saying that a .01 loss of moisture equates to a 5kg loss?

anonymous · Answer

you have 10 pounds that is water and solid, 99% water so 1% solid and 1% of 10 is 0.1

anonymous · Answer

so you have .1 pound of solid, that that does not evaporate
now a day later you have 98% water, meaning the rest , the other 2% is the solid

anonymous · Answer

so the question is now this: 0.1 pounds is 2% of what number?

anonymous · Answer

and the answer is, 0.1 is 2% of 5

anonymous · Answer

@eSpeX yes, that is what i am saying

espex · Answer

@satellite73 It is not a 2% loss of total weight, it is a 1% loss of moisture.

anonymous · Answer

ok we start again
lets change the probem slightly to make it easier
suppose instead of 10 pound you have 100 pounds of watermelon, and it is 99% water, hence 99 pounds water, and one pound solid

espex · Answer

By your calculations, assuming I am reading it right, a 1% loss of moisture resulted in 1/2 of the total weight evaporating.

anonymous · Answer

now after a day, there is still one pound of solid, but the mixture is now 98% water and therefore 2% not water

anonymous · Answer

so you have 1 pound that is 2% of the total, and 1 is  2% of 50

anonymous · Answer

i was stil right with the is/of x %/100 right?

anonymous · Answer

so a day later you have 50 pounds that would be 49 pounds of water and 1 pound of solid

anonymous · Answer

and you can easily check that the answer is right, because if i have 50 pounds, 49 of it water and 1 pound solid, then i have 98% water and 1 pound solid
the answer is correct

anonymous · Answer

i think we lost @Genuine, but the 9.9 is the obvious but totally wrong answer

anonymous · Answer

oh well, looks like genuine is gone. alas

espex · Answer

I see where you're going with this, it is the part that 98% now makes up only 1/2 of what 99% did that I am struggling with.

anonymous · Answer

9.9 kg