on your jury CTION 7 2 Targets Bias or Lack of Precision If a rifleman s gunsight is adjusted incorrectly he might shoot bullets consistently close to 2 feet left of the bull s eye target Draw a sketch of the target with the bullet holes Does this show lack of precision or bias Draw a second sketch of the target if the shots are both unbiased and precise have little variation The rifleman s aim is not perfect so your sketches should show more than one bullet hole Targets Bias or Lack of Precision Again 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 HL 0000000 oooo 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 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 cla the class are three juniors and two seniors Using numbers 1 3 to represent juniors and 4 and 5 to represent seniors sampl out replacement Draw a sample of two people four times or each of parts a b c and d and then fill in the following tab a Use the first line reprinted here from the random number tabl select your sample of two The selections are underlined 02779 72645 32699 86009 Report the percentage of seniors in the sample Count the num 4 s and 5 s and divide by the sample size 2 7 26 Random Letters Samuel Morse suggested in the nineteent century that the letter t made up 9 of the English language Assume this is still correct A random sample of 1000 letters is take from a randomly selected large book and the t s are counted a What value should we expect for our sample percentage of t s b Calculate the standard error c Use your answers to fill in the blanks We expect t s give or take 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 27 ESP A Zener deck of cards has cards that show one of five different shapes with equal representation so that the probability c selecting any particular shape is 0 20 A card is selected randomly and a person is asked to guess which card has been chosen The 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 c her proportion of successes should be about 0 20 give or take som SECTION EXERCISES CHAPTER 7 7 32 Far from Fair Which of the graphs in Exercise 7 31 centered farthest from 0 50 b Use the next line to select your sample of two 31867 91430 45554 85872 Report the percentage of seniors in the sample c Use the next line to select your sample of two 07033 75298 75250 34546 Report the percentage of seniors in the sample d Use the last line to select your sample of two 09084 80623 98948 09541 Report the percentage of seniors in the sample e Fill in the rest of the table below showing the results of the four samples p Population p Sample