Aresearcher conducts an independent-measures study examining how the brain chemical serotonin is related to aggression. one sample of rats serves as a control group and receives a placebo that does not affect normal levels of serotonin. a second sample of rats receives a drug that lowers brain levels of serotonin. then the researcher tests the animals by recording the number of aggressive responses each of the rats display. the data are as follows.

control low serotonin

n = 10 n = 15

m = 14 m = 19

ss = 180.5 ss = 130.0

a. does the drug have a significant effect on aggression? use an alpha level of .05, two

tails.

b. compute cohen

Apair of ordinary dice is rolled. what is the probability that each die will show a number higher than 4. 1. (1/36) 2. (1/12) 3. (1/6) 4. (1/4) 5. (1/3)

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?

The interior angles formed by the side of a hexagon have measures of them up to 720° what is the measure of angle a