## Mami_Garcia01 Group Title HELPPP!!! A science teacher has a supply of 5% hydrochloric acid and a supply of 65% hydrochloric acid (HCl). How much of each solution should the teacher mix together to get 42 mL of 45% HCl for an experiment? (1 point) The teacher will need 14 mL of the 5% solution and 28 mL of the 65% solution. The teacher will need 28 mL of the 5% solution and 14 mL of the 65% solution. The teacher will need 14 mL of the 5% solution and 14 mL of the 65% solution. The teacher will need 28 mL of the 5% solution and 28 mL of the 65% solution. 2 years ago 2 years ago

1. mathmate

Let x=vol. of 65%, then 42-x = vol. of 5% Solve for x in: 0.65x+0.05(42-x) = 42*0.45

2. Hero

x + y = 42 .5x + .65y = 42(.45)

3. Hero

You can eliminate the ones where the mL amount don't add up to 42 mL

4. mathmate

And from the two that remain, choose the choice that requires more 65% than 5%, since 45% is closer to 65% than 5%.

5. Hero

Bro, how do you even find stuff like this from a year ago?

6. mathmate

Thanks! :)