FGCU INVITATIONAL MATH COMPETITION INDIVIDUAL STATISTIC TEST Directions: Answer the questions by bubbling in the best choice on your answer sheet. (1) A coin is tossed 1,000 times and 650 heads are observed. The standard error (rounded to 4 decimal places) of the sample proportion of heads is (a) 0.0003 (b) 0.6500 (c) 0.3500 (d) 0.0158 (2) The median of a data set with 51 observations is 23.5. If the largest observation is increased by a value of 0.5, the new median will be (a) 23 (b) 23.5 (c) 24 (d) 24.5 (3) A sample of 87 observations has a mean of 31.2. If differences are obtained by subtracting the mean from each observation, the mean of the differenced data is (a) 0 (b) 31.2 (c) 1 (d) 15.6 (4) The length of the box in a boxplot represents the (a) median of the sample data (b) middle 50% of the data (c) range of the sample (d) observations that are within 2 standard deviations of the mean 1
2 FGCU INVITATIONAL MATH COMPETITION INDIVIDUAL STATISTIC TEST (5) A histogram of salary data shows that most people get paid between $30,000 and $55,000; however a few people earn salaries above $150,000. The histogram can be described as (a) bell-shaped (b) left-skewed (c) right-skewed (d) uniform (6) What is/(are) the problem(s) with this set of response categories to the question What is your current age? 1-5 5-10 10-20 20-30 30-40 (a) The categories are not mutually exclusive (b) The categories are not exhaustive (c) The intervals are not the same length (d) Both a and b are problems (7) If a baseball coach calculates batting averages, what scale would be used? (a) Interval scale (b) Ratio scale (c) Nominal scale (d) Ordinal scale (8) If we took the 500 people attending a school in New York City, divided them by gender, and then took a random sample of the males and a random sampling of the females, the variable on which we would divide the population is called the (a) Independent variable (b) Dependent variable (c) Stratification variable (d) Sampling variable
FGCU INVITATIONAL MATH COMPETITION INDIVIDUAL STATISTIC TEST 3 (9) Which of the following is a form of nonrandom sampling? (a) Voluntary Response Sampling (b) Cluster Sampling (c) Stratified Sampling (d) Systematic Sampling (10) A number that is calculated directly from a population and that characterizes the population is called a (a) datum (b) statistic (c) sample (d) parameter (11) The type of sampling where each member of the population selected for the sample is returned to the population before the next member is selected is called (a) Sampling without replacement (b) Sampling with replacement (c) Simple random sampling (d) Systematic sampling (12) The process of drawing a sample from a population is known as (a) Sampling (b) Census (c) Survey Research (d) Randomization (13) To determine whether noise affects the ability to solve math problems, a researcher has one group solve math problems in a quiet room and another group solve math problems in a noisy room. The group solving problems in the noisy room completes 15 problems in one hour and the group solving problems in the quiet room completes 22 problems in one hour. In this experiment, the independent variable is and the dependent variable is. (a) The number of problems solved; the difficulty of the problems (b) The number of problems solved; the noise level in the room (c) The noise level in the room; the number of problems solved (d) The noise level in the room; the difficulty of the problems
4 FGCU INVITATIONAL MATH COMPETITION INDIVIDUAL STATISTIC TEST (14) What is the complement of the event, It rains at least two days this week.? (a) It does not rain this week. (b) It rains more than two days this week. (c) It rains fewer than 7 days this week. (d) It rains no more than 2 days this week. (15) The general rule for the union of two sets says P (A B) = P (A)+P (B) P (A B). If A and B are independent, then P (A B) = (a) P (A)P (B) (b) P (A) + P (B) (c) 1 P (B A)P (A) (d) 1 P (A c )P (B c ) (16) Approximately what percentage of scores fall within one standard deviation of the mean in a normal distribution? (a) 34% (b) 95% (c) 99% (d) 68% (17) Let s suppose we are predicting score on a training posttest from number of years of education and the score on an aptitude test given before training. Here is the regression equation Y = 25 +.5X 1 + 10X 2, where X 1 = years of education and X 2 = aptitude test score. What is the predicted score for someone with 10 years of education and a aptitude test score of 5? (a) 25 (b) 50 (c) 35 (d) 80 (18) The standard deviation is (a) the square root of the variance (b) a measure of variability (c) an approximate indicator of how numbers vary from the mean (d) All of the above.
FGCU INVITATIONAL MATH COMPETITION INDIVIDUAL STATISTIC TEST 5 (19) are used to visually examine the relationship between two quantitative variables. (a) Bar graphs (b) Pie charts (c) Line graphs (d) Scatterplots (20) Which of the following measures of center is most preferred when the data are severely skewed? (a) Mean (b) Median (c) Mode (d) Range (21) What would happen (other things equal) to a confidence interval if you calculated a 99 percent confidence interval rather than a 95 percent confidence interval? (a) It will be narrower (b) It will not change (c) The sample size will increase (d) It will become wider (22) If you took 1,000 samples of 50 observations each, calculated the mean of sample, and created a histogram of the sample means, what would the graph show? (a) a population distribution (b) a uniform distribution (c) a sampling distribution (d) a parameter distribution (23) Which of the following statements sounds like a null hypothesis? (a) The coin is not fair (b) There is a correlation in the population (c) The defendant is guilty (d) There is no difference between male and female incomes in the population
6 FGCU INVITATIONAL MATH COMPETITION INDIVIDUAL STATISTIC TEST (24) A good way to get a small standard error is to use a (a) large sample (b) repeated sampling (c) large population (d) small significance level (25) The use of the laws of probability to make inferences and draw statistical conclusions about populations based on sample data is referred to as (a) descriptive statistics (b) inferential statistics (c) sample statistics (d) population statistics (26) A blood test is used to determine whether a person is sick or not. The power of the test is the probability that the test (a) says the person is healthy when they really are. (b) detects an illness when the person is actually healthy. (c) does not find any health issues when the person is truly sick. (d) reports that the person is sick when they are, in fact, infected. (27) A data set has observations 0, 25, 30, 35, and 60. Which observations, if any, are outliers? (a) 0 (b) 25 (c) 60 (d) Both (a) and (c) (28) Based on meteorological records, the probability that it will snow in town XYZ is 0.293. There is a 13.5% chance that it snows and someone sees a groundhog. If a groundhog is spotted, how likely is it to snow? (a) 0.461 (b) 0.040 (c) 0.707 (d) 0.865
FGCU INVITATIONAL MATH COMPETITION INDIVIDUAL STATISTIC TEST 7 (Answer questions 29 and 30.) A randomized experiment was done by randomly assigning each participant either to walk for half an hour three times a week or to sit quietly reading a book for half an hour three times a week. At the end of a year the change in participants blood pressure over the year was measured, and the change was compared for the two groups. (29) This is a randomized experiment rather than an observational study because: (a) Blood pressure was measured at the beginning and end of the study. (b) The two groups were compared at the end of the study. (c) The participants were randomly assigned to either walk or read, rather than choosing their own activity. (d) A random sample of participants was used. (30) The two treatments in this study were: (a) Walking for half an hour three times a week and reading a book for half an hour three times a week. (b) Having blood pressure measured at the beginning of the study and having blood pressure measured at the end of the study. (c) Walking or reading a book for half an hour three times a week and having blood pressure measured. (d) Walking or reading a book for half an hour three times a week and doing nothing.