science
posted by astrid .
Erin must perform a science experiment. She needs to dissolve 10 g of salt in 250 ml of water. She measures the water incorrectly and dissolves the 10 g of salt in 350 ml of water. Now she has no more salt. Explain what Erin can do to make the solution accurate.

She could add more salt.
Solve this proportion to find how much salt is needed in 350 ml.
250 / 350 = 10 / x 
She can't add more salt because she has no more salt.

Oops! Sorry. I didn't read the entire question.
The only other solution I see is to let the excess water evaporate. 
So if she lets the water evaporate, she can use the remaining salt to use it in another cip with 250 ml of water

She only needs to let the excess water (100 ml) evaporate.

How can she make sure its 100 ml?

She can note the amount of salt and water in a flask marked in ml.