1. [2] Two cars are driving directly towards each other such that one is twice as fast as the other. The distance between their starting points is 4 miles. When the two cars meet, how many miles is the faster car from its starting point?
Answer: $\sqrt{\frac{8}{3}}$ Note that the faster car traveled twice the distance of the slower car, and together, the two cars traveled the total distance between the starting points, which is 4 miles. Let the distance that the faster car traveled be $x$. Then, $x+\frac{x}{2}=4 \Longrightarrow x=\frac{8}{3}$. Thus, the faster car traveled $\frac{8}{3}$ miles from the starting point.