Chapter 1 Test Probability and Statistics

Which are the correct ways of making a conclusion in a significance test? Check all that apply

• Type II error

• Type I error

A ___ is described by a symmetric, single-peaked, bell-shaped density curve. Any ___ is completely specified by its degrees of freedom (df). When performing inference about a population mean based on random sample of size n when the population standard deviation is unknown, use a ___ with df=n-1.

All blanks are the same word

The _____ \alpha is the value that we use as a boundary for deciding whether an observed result is unlikely to happen by chance alone when the null hypothesis is true.

A certain Boba machine is designed to fill a 16-ounce cup. When it is working properly, the amount filled follows a Normal distribution with a mean of 16.5 ounces and a standard deviation of 0.3 ounces. If 4 cups of Boba are randomly selected, what is the probability that the sample mean will be less than 16.8 ounces?

• .9772

• .1587

• .8413

• .0228

According to a recent poll, 92% of Americans believe more could be done to end the pandemic. Let's assume this is the parameter value for the population. If you take an SRS of 65 Americans and let p̂ = the proportion in the sample who feel more could be done, is the shape of the sampling distribution of p̂ approximately Normal?

• Yes, because n ≥ 30

• Yes, because np = 59.8

• No, because n(1-p) = 5.2

• No, because 65 ≤ 1/10 N

The time it takes all cross country runners to complete a course has a mean of 32.1 minutes with a standard deviation of 10.2 minutes. What is the probability that an SRS of 36 runners will have a mean completion time greater than 34 minutes?

• .4261

• .5739

• .8681

• .1319

A Gallup Poll asked a random sample of 1240 adults, "Do you play video games?" Suppose the true proportion of all adults who play video games is p = .26.
What is the standard deviation of the sampling distribution of p̂?  Check that the 10% condition is met.

• The 10% condition is met.  σp̂ = .0126

• The 10% condition is not met.

• The 10% condition is met.  σp̂ = .0074

• The 10% condition is met.  σp̂ = .26

In a recent state election, 58% of the voters were Democratic. The total percent of Democratic voters in the state is actually 52%.

• 52% is a statistic and 58% is a parameter.

• 52% is a parameter and 58% is a statistic.

• I am unable to determine parameters with the given information.

• Both 52% and 58% are parameters.