Exam 6: Probability, normal Distributions, and Z Scores

A researcher wants to know the probability of being named on the honor roll from a population where 8% of students are on the honor roll.If the researcher selects a sample of 400 students,then what is the mean number of students expected to be on the honor roll? Hint: This is a binomial distribution,where p = 0.08 and q = 0.92.

The mean,median,and mode are all located at the 50th percentile in a standard normal distribution.

Most behavioral phenomena are believed to approximate the normal distribution.

A distribution of z scores is distributed in what type of unit of measurement?

A researcher records the following assessment data: 42 ± 6 (M ± SD).The researcher only wants to sample participants scoring in the top 20% of this assessment.What is the cutoff score for the top 20% in this example?

A therapist has a goal to reduce the mean number of patient symptoms expressed for a particular disorder to two symptoms per day.Following therapy,she determines that the z score for 2 symptoms per day is 0.Assuming the data are normally distributed,did she reach her goal?

A researcher finds that the average preschool-aged child drinks two cups of milk per day.Assuming these data are normally distributed,the z score for the average cups per day in this example is

A researcher records the following number of birdcalls made during an experimental session with robins: 7.2 ± 0.6 (M ± SD).Assuming these data are normally distributed,what is the probability that robins made more than nine birdcalls during this experimental session?

The z score cutoff for the top 50% of scores in any normal distribution is 0.

A researcher measures the number of tasks completed by participants during a 5-min multitasking session.If the number of tasks completed is distributed normally as 6.3 ± 1.0 (M ± SD)tasks,then what is the probability that participants completed less than eight tasks?

A professor records the following final exam scores: 78 ± 7 (M ± SD).Students scoring in the top 14% get an A. What is the cutoff score for the top 14% in this example?

Which of the following is a possible value for the standard deviation of a normal distribution?

State whether the first area is bigger,the second area is bigger,or the two areas are equal: the area to the left of z = 0.80,or the area to the right of z = -0.80.

What is the z score for scores in the bottom 5%?

In a normal distribution,50% of all data:

The standard normal distribution is normally distributed with a mean of ______ and a variance of ______.

In a normal distribution,the mean can only take on positive values.

The standard normal distribution can be used to estimate probabilities with known raw scores,but it cannot be used to estimate raw scores with known probabilities.

All z scores above the mean are positive,whereas all z scores below the mean are negative.

For a set of data with 25 ± 2.5,at least 95% of scores fall between 20 and 30.