stats exam chapter 5

A researcher determines that students are active about 6012 (MSD) minutes per day. Assuming these data are normally distributed, what is the z score for students being active 48 minutes per week? 1.0 -1.0 0 There is not enough information to answer this question.

-1

What is the z score for scores in the bottom 10%? 1.28 2.32 -2.32 -1.28

-1.28

What is the z score for scores in the bottom 5%? 1.645 -1.645 .4801 The score is not listed in the table.

-1.645

The standard normal distribution is normally distributed with a mean of ____ and a variance of ____. 0; 1 1; 0 any value; any positive value any positive value; any value

0;1

A researcher records the following number of birdcalls made during an experimental session with robins: 7.20.6 (MSD). Assuming these data are normally distributed, what is the probability that robins made more than 9 birdcalls during this experimental session? .9987 .4987 .0013 The probability is not listed in the unit normal table.

.0013

A researcher records the following response times to a visual stimulus: 233.1 (MSD) seconds. Assuming these data are normally distributed, what is the probability that participants responded in 20 seconds or less? .1660 .3340 .6660 The probability is not listed in the unit normal table.

.1660

A researcher has participants choose between three advertisements. She finds that 54 prefer Ad A, 86 prefer Ad B, and 60 prefer Ad C. The probability or proportion of participants preferring Ad B is .86 .60 .43 86

0.43

A therapist goes through her records and finds that 200 of her 400 patients showed significant improvement in mental health over the past year. Hence, the probability of her patients showing significant improvement in mental health is .05 .50 200 400

0.50

A researcher records the following body mass index (BMI) scores for a group of participants: 28.41.6 (MSD). Participants who score between 25 and 30 on this scale are categorized as overweight. What percentage of participants fell in this category? .4834 .1753 .8413 .8247

0.8247

A counselor records the number of disagreements (per session) among couples during group counseling sessions. If the number of disagreements is distributed normally as 4.40.4 (MSD) disagreements, then what proportion of couples disagree at least 4 times during each counseling session? .3413 .1587 .8413 The probability is not listed in the unit normal table.

0.8413

A researcher measures the number of tasks completed by participants during a 5-minute multitasking session. If the number of tasks completed is distributed normally as 6.31.0 (MSD) tasks, then what is the probability that participants completed less than 8 tasks? .0446 .9554 .4554 The probability is not listed in the unit normal table.

0.9554

A professor finds that the students scored a 768 (MSD) on the final exam. On this exam, a score of 90 is an A. Assuming these data are normally distributed, what is the z score for 90 (the cutoff for an A)? 1.75 1.50 1.25 There is not enough information to answer this question.

1.75

What is the z score for scores in the top 2.5%? .675 1.96 .0124 .0250

1.96

A researcher records the following times (in seconds) that it took a group of students to complete an exam: 18±2 minutes (M±SD). How long did it take 80% of students to complete the exam? Less than 16 minutes. 16.32 minutes. Less than 18 minutes 19.68 minutes.

19.68

A researcher records the following time spent sleeping per night (in hours) in a group of participants: 5.81.8 (MSD). The researcher decides to categorize participants who sleep between 6 to 8 hours as moderate sleepers. What percentage of participants fell in this category? about 39% about 11% about 35% about 7%

35%

A researcher records the following assessment data: 426 (MSD). 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? 0.84 47.04 36.96 There is not enough information to answer this question.

47.04

A professor records the following final exam scores: 787 (MSD). Students scoring in the top 14% get an A. What is the cutoff score for the top 14% in this example? 1.08 70.44 85.56 There is not enough information to answer this question.

85.56

A theoretical distribution that evenly distributes data around the mean, median, and mode is called the normal distribution bell-shaped distribution Gaussian distribution all of the above

all of the above

In a normal distribution, 50% of all data: fall above the mean fall below the median fall above and below the mode all of the above

all of the above

Most behavior is believed to ________ a normal distribution. be exactly equal to not resemble at all approximate

approximate

Which of the following is required to locate z scores with a given proportion? Find the z score associated with a given probability. Compute a z-transformation to find the raw score. both A and B none of the above

both A and B

Which of the following is not a step to locate a proportion in a normal distribution? Transform a raw score (x) into a z score. Locate the corresponding proportion for the z score in the unit normal table. Convert a proportion to a standard normal z score.

convert a proportion to a standard normal z score

A researcher visits a population of 1,200 local residents to determine the proportion of local residents who support a new smoking ban. In this case, the sample space is equal to the number of residents who support the new smoking ban equal to the total number (or population) of residents equal to more than just these 1,200 residents unknown

equal to the total number of residents

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 less than 0 greater than 0 exactly equal to 0 There is not enough information to answer this question.

exactly equal to 0

A parent decides to reward her child if he eats an average of at least five bites of his vegetables at dinner during the first week. She finds that her child ate 40.8 (MSD) bites per meal for the first week. Assuming these data are normally distributed, should this parent reward her child? Yes, because the z score for 5 bites is greater than 0. Yes, because the z score for 5 bites is less than 0. No, because the z score for 5 bites is greater than 0. No, because the z score for 5 bites is less than 0.

no because the z score for 5 bites is greater than 0

Two normal distributions are observed. The first distribution has a mean of 12 and a standard deviation of 2. The second distribution has a mean of 0 and a standard deviation of 2. For which distribution will the z score for the mean be larger? The first z distribution. The second distribution. None, the z score will be the same.

none, the z score will be the same

The following distribution most closely approximates a (chart) normal distribution positively skewed distribution negatively skewed distribution multimodal distribution

normal distribution

The proportion or fraction of times an outcome is likely to occur is referred to as probability a random event sample space luck

probability

Which of the following is NOT a characteristic of probability? Probability varies between 0 and 1. Probability can never be negative. Probability can be stated as a fraction or decimal. Probability is most useful for describing fixed events.

probability is most useful for describing fixed events

The normal distribution is symmetrical, which means that scores above the mean are distributed the same as scores below the mean extreme scores are possible in a normal distribution there are an infinite number of possible normal distributions this characteristic has no practical implication

scores above the mean are distributes the same as scores below the mean

A distribution of z scores are distributed in what type of unit of measurement? Binomial outcomes Probabilities Standard deviation units Depends on the shape of the distribution

standard deviation units

Which proportion is largest in a z distribution? The proportion of area above the mean. The proportion of area between z = +1 and z = -1. The proportion of area greater then z = 1.0. The proportion of area less than z = 0.

the area between 1 and -1

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 = 1.00, or the area to the left of z = -1.00. The first area is bigger. The second area is bigger. The two areas are the same.

the first area is bigger

The total number of possible outcomes for a random variable is referred to as probability a random event the sample space the sum

the sample space

State whether the first area is bigger, the second area is bigger, or the two areas are equal: the area to the right of the mean, or the area between z = ±1.00. The first area is bigger. The second area is bigger. The two areas are the same.

the second area is bigger

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. The first area is bigger. The second area is bigger. The two areas are the same.

the two areas are the same

The mean can take on any value and the standard deviation can take on any positive value. Therefore, scores above the mean are distributed the same as scores below the mean extreme scores are possible in a normal distribution there are an infinite number of possible normal distributions this characteristic has no practical implication

there are an infinite number of possible normal distributions

Which of the following is not a step to locate a score in a normal distribution? Locate a z score associated with a given proportion in the unit normal table. Transform the z score into a raw score (x). Transform a raw score (x) into a z score.

transform a raw score into a z score

The unit of measurement distributed along the x-axis of a standard normal distribution is referred to as a standardized score x-score normalized deviation z score

z score