Answer:
CI =[- 4.588; 15.4]
Since the calculated value of t= 4.244 falls in the critical region so we reject H0 and conclude that we are not confident that the mean difference in lifetime between front and rear brake pads is 99.5%
Step-by-step explanation:
The given data is
Car Rear Front d= rear- front
1 40.6 32.5 8.1
2 35.4 27.1 8.3
3 46.6 35.6 11
4 47.3 35.6 11.7
5 38.7 30.3 8.4
6 51.2 41.1 10.1
7 50.6 40.7 9.9
8 45.9 34.3 11.6
<u>9 47.2 36.5 10.7</u>
∑ = 89.8
Let the hypotheses be
H0: ud= 0 against the claim Ha: ud ≠0
The degrees of freedom = n-1= 9-1= 8
The significance level is 0.05
The test statistic is
t= d`/sd/√n
The critical region is ║t║≤ t (0.025,8) = ±2.306
Sd= 7.05434553
d`=∑d/n= 89.8/9= 9.978
Therefore
t= d`/ sd/√n
t= 9.978/ 7.054/√9
t= 4.244
1) Since the calculated value of t= 4.244 falls in the critical region so we reject H0 and conclude that we are not confident that the mean difference in lifetime between front and rear brake pads is 99.5%
2) the confidence interval for the difference of two samples can be calculated by
d ` ± td sd/√n
9.978 ±2.306* 7.054/√9
- 4.588; 15.4
28 x 6 = 168 hours
168 x 9 = $1512
hope this helps x
Using linear function concepts, it is found that the true statements are as follows:
- The number of biology degrees increases by about 2.414 each year after 2000.
- About 73.000 students graduated with degrees in psychology in 2000.
- In 2000, more students graduated with psychology degrees than biology degrees.
<h3>What is a linear function?</h3>
A linear function is modeled by:

In which:
- m is the slope, which is the rate of change, that is, by how much y changes when x changes by 1.
- b is the y-intercept, which is the value of y when x = 0, and can also be interpreted as the initial value.
In this problem, for psychology, the model for the number of graduated students in t years after 2000 is:
P(t) = 2,376t + 73,219.
For biology, it is given by:
B(t) = 2,414t + 56, 545
Hence, the correct statements are:
- The number of biology degrees increases by about 2.414 each year after 2000.
- About 73.000 students graduated with degrees in psychology in 2000.
- In 2000, more students graduated with psychology degrees than biology degrees.
More can be learned about linear function concepts at brainly.com/question/24808124
7 - 3 2/5 =
7 - 17/5 =
35/5 - 17/5 = 18/5 = 3.6