Construct a confidence interval for μd, the mean of the differences d for the population of paired data. assume that the population of paired differences is normally distributed. a test of writing ability is given to a random sample of students before and after they completed a formal writing course. the results are given below. construct a 99% confidence interval for the mean difference between the before and after scores.
before 70 80 92 99 93 97 76 63 68 71 74
after 69 79 90 96 91 95 75 64 62 64 76

Step-by-step explanation:

Group Before After

Mean 80.27 78.27

SD 12.76 12.92

SEM 3.85 3.89

N 11 11

df = 10

standard error of difference = 0.798

The mean of Before minus After equals 2.00

Given a=0.01, |t(0.005, df=10)|=3.17 (check student t table)

So 99% CI is

2±t*s

--> 2±3.17*0.798

--> -0.5 < µd< 4.5

-0.5 < µd< 4.5

54 km / hours

step-by-step explanation:

we need to convert seconds to hours

60 seconds = 1 minutes

60 minutes = 1hour

15 m         60 second   60 minutes

  * *         = 54000 meters/ hour

second     1 minute             1 hour

now we need to convert meters to km

1000 m = 1 km

54000 m       1 km

*   = 54 km / hours

hour               1000m

answer: 4 meters

step-by-step explanation: to you understand 2/3 better you can do 1 divided by 3 = . then multiply that by the 2 which is .66666666666666667 then you would do 6 x .66666666666666667 which is 4.      

hope this .