SOLUTION: A lab technician needs 35 mL of 15% base solution for a certain experiment, but she has only 10% solution and 20% solution. How many milliliters of the 10% and the 20% solutions sh

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Question 1158713: A lab technician needs 35 mL of 15% base solution for a certain experiment, but she has only 10% solution and 20% solution. How many milliliters of the 10% and the 20% solutions should she mix to get what she needs?
The technician will need mL of the 10% solution and mL of 20% solution
Found 2 solutions by greenestamps, ikleyn:
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


Common sense should tell us that, since 15% is halfway between 10% and 20%, the mixture should use equal amounts of the 10% and 20% solutions.

ANSWER: 17.5 mL of each

Algebraically, if required....

x = mL of 10% solution
35-x = mL of 20% solution

The total amount in the two ingredients is 15% of the total 35 mL:

.10%28x%29%2B.20%2835-x%29+=+.15%2835%29

Solve using basic algebra; of course your answer should be 17.5 mL of each.

Answer by ikleyn(52803) About Me  (Show Source):
You can put this solution on YOUR website!
.

Since 15% is exactly half way between the 10% and 20%,

he (or she) needs equal amounts of each original ingredients.


ANSWER.  17.5 mL of each original ingredients.

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Any housewife will say it without any calculations.

(Because she has common sense . . . )