twin moth
Khan Academy has a series of exercises that feature several word problems regarding combining mixtures to get a certain percentage and finding the rate of something. The only problem is that this lesson is like 3-4 lessons in a trench coat, and I'm struggling to get the hang of them.
The problems include stuff like:
- If A does it in 200 minutes and B does it in 400 minutes, how long does it take for both of them to do it? (which I can do to an extent)
- A goes up the stairs at a rate of x and down the stairs at a rate of y. What is the rate all together?
- Mixture A has 3% alcohol and Mixture B has 12% alcohol. If you were to pour Mixture B into Mixture A, how much of Mixture B would it take to make a mixture of 7% alcohol?
These aren't the exact problems, but they usually follow one of those themes. Sometimes, they play around and say stuff like, "A does it in 200 minutes, and it takes 180 minutes for them to do it together. How long does it take for B to do it on his own?" as well.
Does anyone know any resources or advice on how to approach problems like these ones?
lapis fulcrum