Statistics Mid-Term Exam

A student in your class claims he can tell when soda come from a can or a bottle. What elements can you control?

- Amount Given - Same Temperature - Same Type Drink/Brand - Judges Blind - Served in the same type of cup

The correlation coefficient is always between _____ and _____

-1 and 1

Nicole's score on the stats midterm was 80 points. The class average was 75 and the standard deviation was 5 points. What is her Z-Score?

1

Cars in US have an average of 135 horsepower, with a standard deviation of 40. What is the Z-Score for a car with 195 horsepower?

1.5

What is the Median? 121, 124, 132, 142, 151

132

What is the Mean? 121, 124, 132, 142, 151

134

A student​ re-expressing data by taking the logarithm of the response variable. The resulting equation looks like log(y)=1.2+0.1x. Find the value of the response​ variable, y, if x is 2. Round to two decimal places.

25.12

Suppose the mean height for a group of boys could be represented using a normal model, and the mean height was 67'' with a standard deviation of 3. 68% of the boys are between ____-____ inches, 95% of the boys are between ____-____ inches, and 99.7% of the boys are between ____-____ inches.

64-70, 61-73, 58-76

What is the IQR? 9, 10, 12, 13, 13, 13, 15, 15, 16, 16, 18, 22, 23, 24, 24, 25

9.5

The mean score on the last stats test was an 82 with a standard deviation of 5. Your teacher told you your Z-Score was 2. What did you score on the test?

92

The average temperature in January is 37 degrees in Ohio with a standard deviation of 7.5. The average temperature in July in Ohio is 84 degrees with a standard deviation of 4. What would be more rare: A 46 degrees day in January or a 72 degrees day in July?

A 72 Degrees Day in July

If we want to study the relationship between two quantitative variables such as fat and calorie content of​ food, what type of graphical display should be​ made?

A Scatterplot

When using exam scores to predict a student's final grade in class, would they want a positive residual or a negative residual?

A positive residual

Anna and Megan are language majors. Both took final exams in French and Spanish. Anna scored an 83 on each. Megan scored a 71 on the French exam and a 95 on the Spanish exam. The mean of the French exam with 81 with standard deviation of 5. The Spanish exam had a mean of 74 and standard deviation of 15. Which student's overall performance was better?

Anna's Performance

Suave is testing their new line of shampoo on hair condition. They believe the product ay work differently on men than on women, and people of different race. Additionally, they believe whether or not the participants dye their hair could affect the results. What element of control would you use to conduct this survey.

Block by gender, hair type, and whether or not the participant dyes their hair.

A certain poll question​ asked, "In the past 5 years, do you think that things have gotten worse, gotten better, or stayed the same?" The possible responses were "Worse", "Better", "No change", "Don't Know", and "No Response". What kind of variable is the​ response?

Categorical Variable

True or False? Confounding is a method of Control.

False

A certain basketball player on the team shoots free-throws with 60% accuracy. The team is down 2 points at the end of the game. At the buzzer, the player is fouled attempting a a 3-point shot. What is the chance he wins the game for the team? Describe how you would use random numbers to simulate this situation.

Let 0-3 represent a miss and 4-9 represents a make. Generate three random numbers and record the number of makes. If the player makes all 3, they win.

A researcher identified over 100 men over 40 who were not exercising and another 100 men over 40 who were exercising regularly. She followed all the men for several years to see if their was any difference in the rate of heart attacks. This would be a _________ study.

Prospective

A pharmaceutical company conducts an experiment in which a subject takes 75 mg of a substance orally. The researchers measure how many hours it takes for one quarter of the substance to exit the bloodstream. What kind of variable is the company​ studying?

Quantitative Variable

A company sponsoring a new Internet search engine wants to collect data on the ease of using it. Which is the best way to collect the data?

Sample Survey

A researcher wants to study the effect of screen brightness on head ache frequency. The randomly divide 60 participants of a similar age in groups of 3. Each group sets their screen to a specified level of brightness. What is the factor?

Screen Brightness

Shifting​ data, by adding a constant to each data​ value, does not change the​ ______________.

Standard Deviation

Ceramic engineers are testing anew formulation for the material used to make insulators for powerlines. The will try baking the insulators at 4 different temperatures, followed by either slow or rapid cooling. The want to try every combination of the baking and cooling options to see which procedures insulators least likely to break during adverse weather conditions. a. How many factors are there? b. How many treatments are there? c. What is the response variable?

a. 2 (Temperature and Cooling Method) b. 8 c. Strength of insulator in adverse conditions.

Debt = -2,231,226 + 1128(year) with R^2 = 98.2% a. What is the response variable? b. What is the correlation coefficient r? c. Explain in context what the slope of the line means. d. Explain in context what R^2 = 98.2% means.

a. Debt b. .994 c. Debt increases by 1128 per year d. 98.8% of variance in debt is accounted for by year.