MTB > execute 'ml-11-12.mtb'
MTB > Note. Bill Qualls - WCC - BU107
MTB > Note. Mason & Lind, Chapter 11
MTB > Note. 7th edition, page 432, #12
MTB > Note. 8th edition, page 408, #18
MTB >  
MTB > Note. "The Kentucky Highway Department is considering
MTB > Note. a new four-land highway. A number of questions
MTB > Note. have been raised. One of them involves the speed
MTB > Note. of trucks on a four-lane highway with a median
MTB > Note. strip over 50 feet versus a highway with a median
MTB > Note. strip under 50 feet. To research the matter
MTB > Note. further, the speeds of a random sample of trucks
MTB > Note. traveling on the two types of highway were
MTB > Note. measured (speeds are in miles per hour). Based on
MTB > Note. this preliminary sample information and using the
MTB > Note. .01 level, can we say there is a significant
MTB > Note. difference in the speeds of the trucks on the two
MTB > Note. different highways?"
MTB >  
MTB > set into c1
DATA> 55 70 68 67 70
DATA> end
MTB >  
MTB > name c1 'Under50'
MTB >  
MTB > set into c2
DATA> 64 68 70 70 65
DATA> 65 75 63 66 49
DATA> end
MTB >  
MTB > name c2 'Over50'
MTB >  
MTB > describe c1-c2

                N     MEAN   MEDIAN   TRMEAN    STDEV   SEMEAN
Under50         5    66.00    68.00    66.00     6.28     2.81
Over50         10    65.50    65.50    66.37     6.82     2.16

              MIN      MAX       Q1       Q3
Under50     55.00    70.00    61.00    70.00
Over50      49.00    75.00    63.75    70.00

MTB >  
MTB > twosample-t c1 c2;
SUBC> pooled.

TWOSAMPLE T FOR Under50 VS Over50
          N      MEAN     STDEV   SE MEAN
Under50   5     66.00      6.28       2.8
Over50   10     65.50      6.82       2.2

95 PCT CI FOR MU Under50 - MU Over50: (-7.4, 8.4)

TTEST MU Under50 = MU Over50 (VS NE): T= 0.14  P=0.89  DF=  13

POOLED STDEV =       6.66

 
MTB >  
MTB > Note. Since p = .89 > alpha which is .05, do not reject the null hypothes
    > is.
MTB >  
MTB > stop
*** Minitab Release 8.21 *** Minitab, Inc. ***
Storage available 16174