The distribution of random variable R has mean 10 and standard deviation 4. The distribution of random variable S has mean 7 and standard deviation 3. If R and S are independent, what are the mean and standard deviation of the distribution of R−S ? Mean 3 and standard deviation 1

A. Mean 3 and standard deviation 5

B. Mean 3 and standard deviation 7

C. Mean 17 and standard deviation 1

D. Mean 17 and standard deviation 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?

If f(x)=2x-6 and g(x)=3x+9, find (f-g)(x)

If a baby uses 15 diapers in 2 days how many diapers will the baby use in a year