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Anna11 [10]
3 years ago
12

The manager of a fleet of automobiles is testing two brands of radial tires and assigns one tire of each brand at random to the

two rear wheels of eight cars and runs the cars until the tires wear out. The data (in kilometers) follow. Find a 99% confidence interval on the difference in the mean life.
Car Brand 1 Brand 2
1 37734 35202
2 45299 41635
3 36240 35500
4 32100 31950
5 37210 38015
6 48360 47800
7 38200 37810
8 33500 33215
(a) Calculate d=
(b) Calculate sD =
(c) Calculate a 99% two-sided confidence interval on the difference in mean life.
Mathematics
1 answer:
Darya [45]3 years ago
8 0

Answer:

Brand 1    Brand 2    Difference

37734       35202        2532

45299      41635         3664

36240      35500        740

32100      31950         150

37210       38015       −805

48360     47800        560

38200    37810          390

33500    33215        285

Sum of difference = 2532+ 3664+740+150 −805+  560 +390 +285 = 7516

Mean = d=\frac{7516}{8}

Mean = d=939.5

a) d= 939.5

\text{Sample Standard deviation, s} = \sqrt{\dfrac{(x-\bar{x})^2}{n-1}}

=\sqrt{\dfrac{(2532-939.5)^2+(3664-939.5)^2+(740-939.5)^2 ...+(285-939.5)^2}{8-1}}

=1441.21

b)SD= 1441.21

c)Calculate a 99% two-sided confidence interval on the difference in mean life.

confidence level =99%

significance level =α= 0.01

Degree of freedom = n-1 = 8-1 =7

So, t_{\frac{\alpha}{2}}=3.499

Formula for confidence interval = \left( \bar{X} \pm t_{\frac{\alpha}{2}} \times \frac{s}{\sqrt{n}} \right)

Substitute the values

confidence interval = 939.5 \pm 3.499 \times \frac{1441.21}{\sqrt{8}} \right)

confidence interval = 939.5 - 3.499 \times \frac{1441.21}{\sqrt{8}} \right) to  = 939.5 + 3.499 \times \frac{1441.21}{\sqrt{8}} \right)

Confidence interval −843.396\ to  2722.396

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Answer:

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Step-by-step explanation:

-10-18=-28 -28/2=-14

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4/4 plus 4/4 please help
krek1111 [17]
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Akimi4 [234]
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4 0
3 years ago
Substitute this equation x+3y=18 & -x-4y=-25
sveticcg [70]

Answer:

 {x,y} = {3/7,-43/7}

Step-by-step explanation:

System of Linear Equations entered :

  [1]    x + 3y = -18

  [2]    -x + 4y = -25

Graphic Representation of the Equations :

   3y + x = -18        4y - x = -25  

 

 

Solve by Substitution :

// Solve equation [1] for the variable  x  

 

 [1]    x = -3y - 18

// Plug this in for variable  x  in equation [2]

  [2]    -(-3y-18) + 4y = -25

  [2]    7y = -43

// Solve equation [2] for the variable  y  

  [2]    7y = - 43  

  [2]    y = - 43/7  

// By now we know this much :

   x = -3y-18

   y = -43/7

// Use the  y  value to solve for  x  

   x = -3(-43/7)-18 = 3/7  

Solution :

{x,y} = {3/7,-43/7}

5 0
3 years ago
What’s the correct answer for this?
otez555 [7]

Answer:

0.7 + 0.4 - 0.2 = 0.9

Step-by-step explanation:

Let's denote the probabilities as following:

The probability that the show had animals is

P(A) = 0.7

The probability that the show aired more than 10 times is

P(B) = 0.4

The probability that the show had animals and aired more than 10 times is

P(A⋂B) = 0.2

The probability that a randomly selected show had animals or aired more than 10 times is P(A⋃B)

The correct form of  addition rule to determine the probability that a randomly selected show had animals or aired more than 10 times is:

P(A⋃B) = P(A) + P(B) - P(A⋂B) = 0.7 + 0.4 - 0.2 = 0.9

=> Option B is correct

Hope this helps!

7 0
3 years ago
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