Fall 2014 Your height: worth 1 extra credit point To be used in data set for lab. Exam 1

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1 Math 12 Name Fall 2014 Your height: worth 1 extra credit point To be used in data set for lab Exam Score: /75 Exam 1 Total Class Percent to Date For problems 1-10, circle the letter next to the response that best answers the question or completes the sentence. You do not have to show any work or write any explanations here. 2 pts each 1. In statistics, conducting a census means: a) making decisions based on sample results b) checking if a variable is qualitative or quantitative c) collecting information from all members of the population d) collecting a sample with replacement 2. An electronics manufacturer test every 50 th cell phone to verify that it is functioning properly. Identify the kind of sampling that is being used. a) stratified sample b) convenience sample c) systematic sample d) simple random sample 3. A is a number that describes a population. a) parameter b) sample c) statistic d) summary 4. The number of classes in a frequency distribution depends on the size of the data set. In general, the: a) larger the data set, the larger the number of classes b) larger the data set, the smaller the number of classes c) number of classes should be equal to the number of values in the data set divided by 6 d) smaller the data set, the larger the number of classes

2 5. A student is told that his score on an exam was in the 45 th percentile. This means that a) about 55% students in the class scored better than him b) about 55% students in the class scored worse than him c) about 55 of the students in the class scored better than him d) about 55 of the students in the class scored worse than him 6. Which of the following measures can have more than one value? a) mean b) median c) mode d) standard deviation 7. The histogram shown below is... a) skewed left b) skewed right c) bell-shaped d) uniform If point A, B, and C all represent measures of central tendency (measures of center), then point A probably represents the. a) mean b) median c) mode point C probably represents the. a) mean b) median c) mode Rel. Freq. A B C Variable Min value = 5 Max value = A rough estimation of the standard deviation of the data values in the histogram could be a) 7 b) 21 c) 105 d) 115 For problems 11-18, make sure to show work where possible! Using the dotplot graph below, answer the following questions: 6 pts 11. What is the mode(s) of the distribution? 12. How big is the sample size? 13. Find the range of the data set:

3 14. The following data set represents number of ice-creams consumed during the month of July, by a sample of six college students in Santa Cruz: 2, 9, 4, 12, 0, pts a) Calculate the mean number of ice-creams consumed using the appropriate formula. Include the appropriate symbol and units in your answer. b) Calculate the median. Include correct units. c) Calculate the standard deviation using appropriate formula. Show all your work! Include correct notation and units of measurements. Round final answer to one decimal. 15. The following population parameters were obtained from a graphing calculator. 5 pts 1-Var Stats x = 61 x = x = Sx = σ x = 6 n = 14 Assuming the population is bell-shaped, between what two values will approximately 95% of the population be?

4 16. Suppose you have the following histogram 7 pts a) What is the variable in this dataset? b) How many observations are in this data set? c) Is the data set grouped or ungrouped? 17. Use the sample frequency distribution below to answer the following: 10 pts a) Find the relative frequency for the last class (20-24) b) Approximate the sample mean for this dataset Class Frequency Gina and Stewart are surf-fishing on the Atlantic coast, where both bluefish and pompano are common catches. The mean length of a bluefish is 264 millimeters with a standard deviation of 60 mm. For pompano, the mean is 137 mm with a standard deviation of 27 mm. 5 pts Stewart caught a bluefish that was 284 mm long, and Gina caught a pompano that was 186 mm long. Who caught the longer fish, relative to fish of the same species? Use z-scores to support your answer.

5 19. Use the boxplot below to answer the questions: 6 pts a) Estimate the third quartile, Q 3 b) Estimate the 25 th percentile c) How many outliers, if any, does the dataset have? 20. Which of the bell-shaped graphs below has the biggest standard deviation? 2 pts 21. Which one of the following measurements the least sensitive to extreme values / outliers (most restistant)? 2 pts a) mean b) median c) standard deviation d) range That s it! Please remember to bring lecture notes for chapter 4 tomorrow!