Princeton and Summitville are 320 miles apart. A train leaves Princeton heading toward Summitville at the same time a train leaves Summitville heading toward Princeton. One train is moving at a speed of 35 mph, and the other is moving 45 mph. How long will they travel before they meet?

If a fair 6 sided cube is rolled 60 times, theoretically how many times should you expect to roll a 4 or a 5?

Asmall (but heavy) particle placed in a glass of water will follow a zigzag motion because the particle will bounce off of the water molecules it meets. this is called brownian motion. a physicist simulates this on a computer, by varying the distance a particle can travel (called the mean free length), on average, before it collides with a water molecule and assigning the change in motion to be one of 8 directions, each with a similar probability. by running the simulated particle (with the same mean free length) many times she determines that it should take 15 seconds, on average, for the particle to fall to the bottom, with a standard deviation of 1.5 seconds. next she lets a real particle fall through a glass of water and finds that it took 18 seconds. what does she conclude, and why?

Agreeting card company can produce a box of cards for $7.50. if the initial investment by the company was $50,000, how many boxes of cards must be produced before the average cost per box falls to $10.50?