A car manufacturer created a new voice-control system that allows drivers to have limited use of their phones while keeping both hands on the wheel. They want to know if the system results in drivers making fewer mistakes, so they recruit volunteers for an experiment. Each subject is randomly assigned to one of three groups: voice-controlled phone use, regular phone use, or no phone use at all. Subjects drive the same simulated course while researchers send notifications at set moments to the drivers who can use phones. The researchers will then compare how many mistakes are made between the groups.
What is the primary purpose of including a group who doesn't use a phone at all?

The probability that a u.s. resident has traveled to canada is 0.18 and to mexico is 0.09. a. if traveling to canada and traveling to mexico are independent events, what is the probability that a randomly-selected person has traveled to both? (page 109 in the book may ) b. it turns out that only 4% of u.s. residents have traveled to both countries. comparing this with your answer to part a, are the events independent? explain why or why not. (page 119 may ) c. using the %’s given, make a venn diagram to display this information. (don’t use your answer to part a.) d. using the conditional probability formula (page 114 in the book) and the %’s given, find the probability that a randomly-selected person has traveled to canada, if we know they have traveled to mexico.