A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 one year ago
PERCENTAGES QUESTION :)
Two beakers of equal volume
Beaker A contains 30% salt
Beaker B contains 10% salt
How many ounces of solution A should be added to solution B, so that the resulting solution is 20% salt?
anonymous
 one year ago
PERCENTAGES QUESTION :) Two beakers of equal volume Beaker A contains 30% salt Beaker B contains 10% salt How many ounces of solution A should be added to solution B, so that the resulting solution is 20% salt?

This Question is Closed

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so far, I let x be the amount of solution in Beaker A. then, 30% of that is the amount of salt in A....same for B...

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3Let's try 10 liters. 10 liters of A has 3 litres salt. 10 liters of B has 1 litres salt. You end up with 20 liters with 4 litres salt. 4 litres out of 20 litres is 20%

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Okay, yep, I;m following so far....

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3Since the concentration you want is exactly the average of the two concentrations you start with, the same amounts of A and B are used.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Oki doki, that makes sense  there might be a problem with the worked solution – its talking about ounces, and I have no information about how many ounced the beakers started out with....

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3Use ounces where I used litres.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0heres the part that dosnt make any sense to me in the worked solution: "the resulting solution will be 50 + x ounces and its concentration of salt will be 20%(50+x)....

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0im guessing instead of your 10L base, theyve used 50 ounces?

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3Is there any info missing from the question you posted? Where does the number 50 come from in the solution?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0thats exactly my problem...

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3Beaker A has x ounces of 30% salt solution. Beaker B has x ounces of 10% salt solution. (Both beakers have x amount because we are the beakers have equal volume.)

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3x ounces of solution B has 0.1x ounces of salt.

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3Now we need to start adding solution A to solution B until we have a new solution that is 20% salt.

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3Let's say we add y ounces of solution A to solution B.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0To do that, we need to find the volume in A containing a concentration of 10%?

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3y ounces of solution A has 0.3y ounces of salt

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3We will have a total of salt: 0.3y + 0.1x Ok?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Yep, all good so far. Thanks for going through it with me.

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3Next, we will have a total amount of solution of: x + y Ok?

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3We want the new solution to have a concentration of 20% salt. 20% = 0.2 That means \(\dfrac{0.3y + 0.1x}{x + y } = 0.2\)

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3Now let's solve that equation and what we get.

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3\(\dfrac{0.3y + 0.1x}{x + y } = 0.2\) \(0.3y + 0.1x = 0.2(x + y)\) \(0.3y + 0.1x = 0.2x + 0.2y\) \(0.1y = 0.1x\) \(y = x\) Correct.

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3Since we chose x to be the amount of solution B and y to be the amount of solution A, we see the amounts must be the same no matter how much each beaker has.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0So do you think that they made x=y=50 ounces?

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3That's what I am thinking.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Yeah, okay. Well thanks for going through it with me in detail. Appreciate your work :)

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3Before the part of the solution you quoted above mentioning 50 + x, was there any mention of 50?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0their equation is exactly what you had, except they made 50=y for some reason: 10%50 + 30%x = 20%(50+x) I understand the equation now, thank you. And no. No mention anywhere of 50 :(

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Also, just wondering if you know how to change the username on open study? i can find the change passwords under settings, but is it even possible to change usernames?

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3I guess they just assumed they would use 50 ounces of one solution, and then they found how many ounces of the other solution they needed. It turns out to be 50, of course, bec now we know it's the same amount of both solutions.

mathstudent55
 one year ago
Best ResponseYou've already chosen the best response.3I don't know if you can change username in OS.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Yes, I reckon you're right on that one. Okay then, thank you!
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.