# A telephone survey uses a random digit dialing machine to call subjects. The random digit dialing machine is expected to reach a live person 15% of the time. In eight attempts, what is the probability of achieving exactly two successful calls?

- A telephone survey uses a random digit dialing machine to call subjects. The random digit dialing machine is expected to reach a live person 15% of the time. In eight attempts, what is the probability of achieving exactly two successful calls?

- The prevalence of a trait is 76.8%.

- In
a simple random sample of
*n*= 5, how many individuals are expected to exhibit this characteristic? - How
many would you expect to see with this characteristic in a simple random sample
of
*n*= 10? - What
is the probability of seeing nine or more individuals with this characteristic
in a simple random sample of
*n*= 10?

- Linda
hears a story on National Public Radio stating that one in six eggs in the
United States are contaminated with
*Salmonella*. If*Salmonella*contamination occurs independently within and between egg cartons and Linda makes a three egg omelet, what is the probability that her omelet will contain at least one*Salmonella*contaminated egg?

- Suppose that heights of 10-year old boys vary according to a Normal distribution with µ = 138 cm and σ = 7 cm.

- What proportion of this population is less than 150 cm tall?
- What proportion is less than 140 cm in height?
- What proportion is between 150 and 140 cm?

- The
Wechsler Adult Intelligence Scale scores are calibrated to vary according to a
normal distribution with µ = 100 and σ = 15. What Wechsler scores cover the
middle 50% of the population? In other words, identify the 25
^{th}percentile and 75^{th}percentile of the population.

- Suppose that scores on the biological sciences section of the Medical College Admissions Test (MCAT) are normally distributed with a mean of 9.2 and a standard deviation of 2.2. Successful applicants to become medical students had a mean score of 10.8 on this portion of the test. What percentage of applicants had a score of 10.8 or greater?

- A
survey selects a simple random sample of
*n*= 500 people from a town of 55,000. The sample shows a mean of 2.30 health problems per person (standard deviation = 1.65). Based on this information, say whether each of the following statements is*true*or*false*. Explain your reasoning in each instance.

- The standard deviation of the sample mean is 0.074.
- It is reasonable to assume that the number of health problems per person will vary according to a normal distribution.
- It is reasonable to assume that the sampling distribution of the mean will vary according to a normal distribution.

- Ten
people are given a choice of two treatments. Let
*p*represent the proportion of patients in the patient population who prefer treatment A. Among the 10 patients asked, 7 preferred method A. Assuming there is no preference in the patient population (i.e.,*p*= 0.5), calculate P(*X*> 7).

- A simple random sample of 18 male students at a university has an average height of 70 inches. The average height of men in the general population is 69 inches. Assume that male height is approximately normally distributed with σ = 2.8 inches. Conduct a two-sided hypothesis test to determine whether the male students are significantly taller than expected. Show all hypothesis testing steps.

- True
or false? The
*p*-value refers to the probability of the data or data more extreme assuming the null hypothesis.

- A researcher fails to find a significant different in mean blood pressure in 36 matched pairs. The standard deviation of the difference was 5 mmHg. What was the power of the test to find a mean difference of 2.5 mmHg at α = 0.05 (two-sided)?