Math 221A Exam 1: 1.You want to study how effective a particular...

Math 221A Exam 1:

1.You want to study how effective a particular medication is at treating the flu. you plan to sample a group of people with the flu and administer the medication. below are the few things you could measure on each patient to answer your research question. for each one, indicate whether it is a quantitative or categorical variable:

1The number of symptoms the patient exhibits after two days on medication: quantitative or categorical variable?

2A patient's self-assessment of the severity of symptoms is mild, moderate, or severe after two days on medication: quantitative or categorical variable?

3The types of symptoms the patient exhibits after two days on medication: quantitative or categorical variable?

4The number of days a patient takes the medication before the symptoms are completely gone: quantitative or categorical variable?

2. A Health Science researcher was studying the health of teenagers in Georgia. He wanted to see if those who played the game Pokmon Go exercised more than those who did not. The researcher randomly chose 50 teenagers that have played Pokmon Go and 50 who have not. He then asked all hundred teenagers to keep track of how many miles they walk outside for a month. The researcher made no attempt to influence the amount of they walked but asked them to only go about their day as usual.

Part 1: in the study above, what is the population of the study?

A.All teenagers in Georgia

B.The hundred teenagers from Georgia

C.The 50 teenagers who played the game Pokmon Go

D.The 50 teenagers who do not play the game Pokmon Go

Part 2: In the previous question, what is the sample of the study?

A.All teenagers in Georgia

B.The hundred teenagers from Georgia

C.The 50 teenagers who played the game Pokmon Go

D.The 50 teenagers who do not play the game Pokmon Go

3. You want to know the mean difference in ages between husband and wife of married LDS couples in the Rexburg area. you randomly select a number of wards within the area and survey every married couple within those selected wards. 509 couples agreed to answer the survey question. use this information to answer both parts:

Part 1: Is this an observational study or an experiment?

A.Experiment because you had control of which wards were sampled.

B.Observational study because you do not try to interfere with the subjects or influence the results in any way.

C.Experiment because you interact with the couple when you ask your survey question

D.Observational study because your data is quantitative

Part 2: which sampling method was used in your study of age differences?

A.Convenience sampling

B.Simple random sampling

C.Stratified sampling

D.Cluster sampling

E.Systematic sampling

4. In order to estimate the mean weight of all students at BYU-Idaho a random sample of 50 students was collected from each class rank (50 freshmen, 50 sophomores, 50 juniors, and 50 seniors) what sampling method was used here?

A.Sample random sample

B.Convenience sampling

C.Stratified sampling

D.Cluster sampling

E.Systematic sampling

5. You collected a random sample of 10 songs in your library and recorded the length of each song (in minutes). use the data below for all the three parts that follow. report all your answers in minutes, rounded to 3 decimal places.

3.07

4.37

4.74

2.39

3.68

3.49

2.97

4.47

4.42

2.46

Part 1: what is the mean length of the songs in your library?

Part 2: using the same information is above what is the standard deviation of the music length?

Part 3: using the same information as above what is the median music length observed?

6. You decided to be more financially responsible, so you have logged the expense of fuel every time you filled up your car. when you were looking at your data on a spreadsheet you noticed that one entry was significantly larger than all the other entries. you know that your car cannot hold that much gas, so it must have been a mistake. use this information for both parts:

Part 1: how would removing that entry influence the mean of the data?

A.The mean will increase.

B.The mean would stay the same.

C.The mean would decrease.

D.With the information given it cannot be determined how/if the mean would change.

Part 2: How would removing that entry influence the median of the data?

A.The median will increase.

B.The median would stay the same.

C.The median would decrease.

D.With the information given it cannot be determined how/if the median will change.

7. According to one study, Americans have a mean of 556 alcoholic drinks per year. while the median drinks per year is 7. based on this information what can you conclude about the shape of the distribution of alcoholic drinks per year for Americans?

A.It is right-skewed

B.it is less skilled

C.it is symmetric

D.it is uniform

8. The U.S Census Bureau publishes data about how much time in minutes people spend commuting to work. you use their data to determine your typical commute time has a z-score of minus -2.01 what is the best way to interpret the z-score?

A.Your commute time is roughly half as long as the mean commute time

B.there is a 2.01% chance that a randomly selected commuter will have a shorter commute time than you

C.your commute time is 2.01 minutes shorter than the mean commute time

D.your commute time is 2.01 standard deviations shorter than the mean commute time

9. A team of Math 221 students was interested in the mean number of Facebook friends a Facebook user has. they randomly picked 100 Facebook users and recorded the number of Facebook friends for each user. Then, from those observations, they calculated a mean of 483. Is this value a parameter or statistic?

A.Parameter since it describes the sample

B.parameter since it describes the entire population

C.statistic since it describes the sample

D.statistic since it describes the entire population

10. You work for a pharmacy, and monthly sales of asthma inhalers in your pharmacy follow a normal distribution with a mean of 191 inhalers per month and a standard deviation of 21. due to a storm, the next shipment of inhalers did not arrive. the pharmacy only had 163 inhalers currently in stock and available to sell for the current month. use this information for both parts:

Part 1: what is the z-score corresponding to selling 163 inhalers?

Part 2: what is the probability that the 163 inhalers are enough to meet that demand for the month (in other words what is the probability that you will sell less than 163 inhalers this month)?

11. A candy company produces thousands of gummy worms each day. the gummy worm bags are known to have a mean weight of 7 oz and a standard deviation of .08 oz. the distribution of their weights is known to be skewed right. the company routinely sampled 35 bags of gummy worms to check if the quality and weight of the gummy worms are up to company standards. use this information to answer the next three parts:

Part 1? what is the mean of the distribution of all possible sample means?

Part 2: what is the standard deviation of the distribution of all possible sample means?

Part 3: what is the shape of the distribution of all possible sample means?

A.Normal, due to the central limit theorem

B.Normal, due to the law of large numbers

C.skewed right, the sample size is not large enough to make it normal

D.it cannot be determined from the information given

12. As part of your application to Graduate School you are required to take a standardized test. after taking the test you how told that you scored in the 63rd percentile. what does this mean?

A.Your score was 63% lower than the mean score

B.63% of scores were the same or lower than your score

C.63% of scores were the same or better than your score

D.your score was .63 standard deviation greater than the mean score

E.you got 63% on the exam

13. A particular type of fishing line has a breaking point at a mean of 12 lbs with a standard deviation of 1.25 lbs. a sample of 30 fishing lines were stretched to their breaking point and the amount of force applied at the time they broke was recorded. use this information for both parts:

Part 1: what is the probability of obtaining a sample mean greater than 12.2 lbs?

Part 2: this same mentioned fishing line advertises that it can hold 11.75 lbs without breaking. what is the probability a sample of 30 fishing lines will yield a mean less than the advertised strength of 11.75 lbs?

14. You want that gaming video you posted on YouTube a week ago to get many views on the website. One website report that YouTube Gaming videos have a mean of 3,050 views. the distribution of views per video was assumed to be normal with a standard deviation of 549 views. use information to answer the next 3 parts:

Part 1: how many views must your video have to be in the 80th percentile? (round your answer to the nearest whole number?

Part 2: Find the probability that a randomly selected gaming video on YouTube will have between 2700 to 3400 views?

Part 3: Find the probability that a random sample of 36 YouTube Gaming videos will have a mean number of views greater than 2953 views?

15. which option best describes the main benefit of randomizing when selecting a sample or assigning subjects to treatments?

A.It reduces variability in the resulting data

B.it is a more efficient alternative to blinding

C.it reduces the potential risk of bias

D.it leads to a more normal dataset