Question

A survey of drivers in the United States found that 15% never use a cell phone while driving. Suppose that drivers arrive at random at an auto inspection station.

If the inspector checks 10 drivers, what is the probability that at least one driver never uses a cell phone while driving? (Round your answer to the hundredth.)

Suppose the inspector checks 1000 drivers. Use the normal approximation to the binomial distribution to find the approximate probability that at least 13% of these drivers never use a cell phone while driving. (Express your answer with 4 decimal places.)

If the drivers are inspected sequentially as they arrive randomly at the inspection station, what is the probability that the first driver who uses a cell phone while driving is the third driver checked? (Express your answer with 4 decimal places.)

What is the expected number of drivers who must be checked to find the first who never uses a cell phone while driving? (Round to the nearest whole number.)

  

What is the expected number of drivers who must be checked to find the first driver who uses a cell phone while driving? (Round to the nearest whole number.)

If it costs $5 to question each driver, what is the expected cost and standard deviation of questioning up to and including the first driver who uses a cell phone while driving?

Expected Cost:     

Standard deviation:  

Answer 1