How many four-letter code words are possible using the letters in iowa if (a) the letters may not be repeated? (b) the letters may be repeated

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?

Elizabeth is using a sample to study american alligators. she plots the lengths of their tails against their total lengths to find the relationship between the two attributes. which point is an outlier in this data set?

An airplane travels at an unknown elevation before it descends 3 miles to an elevation of 15 miles. find the elevation of the plane before its descen.