tongjixue（tongjixue）.docVIP

tongjixue（tongjixue） Statistics, Fourth Edition The fourth chapter is the answer to exercises 4.1 (1): M0=10 mode: =n+1/2=5.5; median median position, the average number of Me=10: (2) QL position =n/4=2.5, QL=4+7/2=5.5; QU position =3n/4=7.5, QU=12 (3) (4) the average number is less than the median and mode, so the car sales for the left skewed distribution. 4.2 (1) from the data in the table can be seen, the frequency of age most is 19 and 23, so there is a mode, namely M0=19 and M0=23. After sorting the raw data, the median is computed as the median position = n+1/2=13, and the value at the thirteenth position is 23, so the median is Me=23 (2) QL position =n/4=6.25, QL==19; QU position =3n/4=18.75, QU=26.5 (3) average 600/25=24, standard deviation (4) skewness kurtosis coefficient SK=1.08, K=0.77 (5) analysis: from the mode, median and average number, the number of Internet users at the age of 23-24 years old accounted for the majority of. Because the standard difference is larger, it shows that there is a big difference between the age of Internet users. From the skewness coefficient, the age distribution is right skewed, so the skewness is very large due to the skewness coefficient is greater than 1. Because the coefficient of kurtosis is positive, so the peak distribution. 4.3 (1) stemand leaf as follows: stem leaf frequency Five Six Seven Five 678 13488 One Three Five (2) 63/9=7, (3) because the average of the two queues is different, the discrete coefficients are used to compare. The first queuing mode: v1=1.97/7.2=0.274; v2=0.714/7=0.102., because V1 V2, shows that the first queuing mode is more discrete than the second queuing methods. (4) choose the method two, because the average waiting time of the second queues is shorter and the degree of dispersion is smaller than the first queuing mode. 4.4 (1) 8223/30=274.1 Median position =n+1/2=15.5, Me=272+273/2=272.5 (2) QL position =n/4=7.5, QL== (258+261) /2=259.5; QU position =3n/4=22.5, QU= (284+291) /2=287