Large stadiums rely on backup generators to provide electricity in the event of a power failure. Assume that emergency backup generators fail 22% of the times when they are needed (based on data from Arshad Mansoor, senior vice president with the Electric Power Research Institute). A stadium has three backup generators so that power is available if at least one of them works in a power failure. Find the probability of having at least one of the backup generators working given that a power failure has occurred. Does the result appear to be adequate for the stadium's needs?

Study of why EMS workers leave the job. A study of fulltime emergency medical service (EMS) workers published in the Journal of Allied Health (Fall 2011) found that only about $3 \%$ leave their job in order to retire. (See Exercise $3.45$, p. 158.) Assume that the true proportion of all fulltime EMS workers who leave their job in order to retire is $p=.03$. In a random sample of 1,000 full-time EMS workers, let $\hat{p}$ represent the proportion who leave their job in order to retire. Describe the properties of the sampling distribution of $\hat{p}$.

Refer to the accompanying table showing results f rom a Chembio test for hepatitis C among HIV-infected patients (based on data f rom a variety of sources).

$$\begin{matrix} \text{ } & \text{Positive Test Result} & \text{Negative Test Result}\\ \text{Hepatitis C} & \text{335} & \text{10}\\ \text{No Hepatitis C} & \text{2} & \text{1153}\\ \end{matrix}$$

Find the probability of selecting a subject with a negative test result, given

that the subject has hepatitis C. What would be an unfavorable consequence of this error?

Refer to the accompanying table showing results f rom a Chembio test for hepatitis C among HIV-infected patients (based on data f rom a variety of sources).

$$\begin{matrix} \text{ } & \text{Positive Test Result} & \text{Negative Test Result}\\ \text{Hepatitis C} & \text{335} & \text{10}\\ \text{No Hepatitis C} & \text{2} & \text{1153}\\ \end{matrix}$$

Find the negative predictive value for the test. That is, find the

probability that a subject does not have hepatitis C, given that the test yields a negative result. Does the result make the test appear to be effective?

A survey with 12 questions is designed so that 3 of the questions are identical and 4 other questions are identical (except for minor changes in wording). How many different ways can the 12 questions be arranged?

Study of why EMS workers leave the job. A study of fulltime emergency medical service (EMS) workers published in the Journal of Allied Health (Fall 2011) found that only about 3% leave their job in order to retire. (See Exercise $3.45$, p. 158.) Assume that the true proportion of all fulltime EMS workers who leave their job in order to retire is $p=.03$. In a random sample of 1,000 full-time EMS workers, let $\hat{p}$ represent the proportion who leave their job in order to retire. Compute $P(\hat{p}>.025)$. Interpret this result.

In the New Jersey Pick 6 lottery game, a bettor selects six different numbers, each between I and 49. Winning the top prize requires that the selected numbers match those that are draw n, but the order does not matter. Do calculations for winning this lottery involve permutations or combinations? Why?

Potassium superoxide, $KO_2$, is employed in a self-contained breathing apparatus used by emergency personnel as a source of oxygen. The reaction is\

$4KO_2(s) + 2H_2O(l) \longrightarrow 4KOH(s) + 3O_2(g)$\

Say a self-contained breathing apparatus is charged with 750 g $KO_2$ and then is used to produce 195 g of oxygen. Was all of the $KO_2$ consumed in this reaction? If the $KO_2$ wasn’t all consumed, how much is left over and what mass of additional $O_2$ could be produced?

A nuclear reactor is equipped with two independent automatic shutdown systems to shut down the reactor when the core temperature reaches the danger level. Neither system is perfect. System A shuts down the reactor 90% of the time when the danger level is reached. System B does so 80% of the time. The reactor is shut down if either system works.

Now simulate 100 trials of the reactor's response to an emergency of this kind. Estimate the probability that it will shut down. This probability is higher than the probability that either system working alone will shut down the reactor.

Myrna White is a mobile housekeeper. The price for a standard house cleaning is $150 and takes 5 hours. Each worker is paid$25/hour, uses $15 of materials and$0.50 per mile to use their own vehicle to travel from job to job. The average job is 5 miles. Arniz Meyroyan has a family reunion at her house and needs her house freshened up. She offers $75 for this emergency tidy-up service. This service includes vacuuming and cleaning floors, dusting, and cleaning the bathrooms. Only$5 of materials would be used.

Myrna White is a mobile housekeeper. The price for a standard house cleaning is $150 and takes 5 hours. Each worker is paid$25/hour, uses $15 of materials and$0.50 per mile to use their own vehicle to travel from job to job. The average job is 5 miles. Arniz Meyroyan has a family reunion at her house and needs her house freshened up. She offers $75 for this emergency tidy-up service. This service includes vacuuming and cleaning floors, dusting, and cleaning the bathrooms. Only$5 of materials would be used.

B. If a $25 surcharge was included to make the price of$100 how would the differential income change?

The following table, reproduced from earlier exercise, gives the probability distribution of the number of patients who enter Millard Fellmore Memorial Hospital's emergency room in a given hour.

$$\begin{array}{l|ccccccc} \hline \text { Patients per hour } & 0 & 1 & 2 & 3 & 4 & 5 & 6 \\ \hline \text { Probability } & .2725 & .3543 & .2303 & .0998 & .0324 & .0084 & .0023 \\ \hline \end{array}$$

Calculate this probability distribution's mean and standard deviation.

A patient is admitted to the emergency department with suspected carbon monoxide poisoning. Even though the patient's color is ruddy and not cyanotic, the nurse understands the patient is at a risk for decreased oxygen-carrying capacity of blood because carbon monoxide does which of the following:

1. Stimulates hyperventilation, causing respiratory alkalosis
2. Forms a strong bond with hemoglobin, thus preventing oxygen binding in the lungs
3. Stimulates hypoventilation, causing respiratory acidosis
4. Causes alveoli to overinflate, leading to atelectasis

Two small liquid-propellant rocket motors are mounted at the tips of a helicopter rotor to augment power under emergency conditions. The diameter of the helicopter rotor is $7 \mathrm{~m}$, and it rotates at $1 \mathrm{rev} / \mathrm{s}$. The air enters at the tip speed of the rotor, and exhaust gases exit at $500 \mathrm{~m} / \mathrm{s}$ with respect to the rocket motor. The intake area of each motor is $20 \mathrm{~cm}^2$, and the air density is $1.2 \mathrm{~kg} / \mathrm{m}^3$. Estimate the power provided by the rocket motors. Ignore the mass rate of flow of fuel in this calculation.

An emergency cell phone charger requires you to turn a small crank in order to create the energy needed to recharge the phone’s battery. If you turn the crank 120 times per minute, the total number r of revolutions that you turn the crank is given by r = 120t where t is the time (in minutes) spent turning the crank. a. Graph the function and identify its domain and range. b. Identify the domain and range if you stop turning the crank after 4 minutes. Explain how this affects the appearance of the graph.