Apharmacy wants to survey its customers to find out which brand of toothpaste they prefer. which survey methods are likely to be biased? select each correct answer.
a: a survey is sent to the customers who are on the pharmacy’s frequent buyer list. b: those customers who buy toothpaste with a coupon are selected, and the toothpaste brand they purchased is recorded. c: one hundred people from the pharmacy’s customer list are selected at random, called on the phone, and asked. d: every 10th customer who enters the pharmacy on 1 day is selected and asked.

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?

Consider the proof. given: segment ab is parallel to line de. prove: what is the missing statement in step 5?

Place the following steps in order to complete the square and solve the quadratic equation,