a If a rifleman s gunsight is adjusted correctly but he has shaky arms the bullets might be scattered widely around the bull s eye target Draw a sketch of the target with the bullet holes Does this show variation lack of precision or bias Explain how you can tell from the widths of the graphs which has the largest sample n 40 and which has the smallest sample n 10 1 amount Each dot in the dotplots represents the proportion of suc cess for one person For instance the dot in Figure A farthest to the right represents a person with an 80 success rate One dotplot rep TRY 7 33 What Is the Proportion of Seniors Example 5 A resents an experiment in which each person had 10 trials another shows 20 trials and a third shows 40 trials population of college students is taking an advanced math class In the class are three juniors and two seniors Using numbers 1 2 and 3 to represent juniors and 4 and 5 to represent seniors sample with out replacement Draw a sample of two people four times once in each of parts a b c and d and then fill in the following table reprinted here from the random number table to select your sample of two The selections are underlined Use the 02779 72645 32699 86009 Report the percentage of seniors in the sample Count the number of 4 s and 5 s and divide by the sample size 2 C T 0 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 1 0 Sample Proportion 7 28 ESP Again In the graph for Exercise 7 27 explain how you can tell from the shape of the graphs which has the largest sample size and which has the smallest sample size 7 29 Standard Error Which of the dotplots given in Exercise 7 27 has the largest standard error and which has the smallest stan dard error 7 30 Bias Assuming that the true proportion of success for the trials shown in the graph for Exercise 7 27 is 0 2 explain whether any of the graphs shows bias graph below shows a computer simulation of experiments in which a person was asked to guess which card had been selected for a large number of trials If the person does not have ESP then his or her proportion of successes should be about 0 20 give or take some 7 31 Fair Coin One of the graphs shows the proportion of heads from flipping a fair coin 10 times repeatedly The others do not Which graph represents the coin flips Explain how you know SECTION EXERCISES 7 32 Far from Fair Which of the graphs in Exercise 7 31 is centered farthest from 0 50 CHAPTER 7 b Use the next line to select your sample of two 31867 85872 91430 45554 Report the percentage of seniors in the sample c Use the next line to select your sample of two 75250 34546 75298 Report the percentage of seniors in the sample 07033 d Use the last line to select your sample of two 98948 09541 80623 Report the percentage of seniors in the sample 09084 e Fill in the rest of the table below showing the results of the four samples Repetition 1 from part a 2 from part b 4 p Population Proportion of Seniors 2 5 0 4 347 p Sample Proportion of Seniors 1 2 0 5 Error pp 0 5 0 4 0 1 7 34 Simulation From a very large essentially infinite population of which half are men and half are women you take a random sample with replacement Use the following random number table and assume each single digit represents selection of one person the odd numbers represent women and the even numbers 0 2 4 6 8 men a Start on the left side of the top line with 118 and count 10 people What percentage of the sample will be men