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gulaghasi [49]
3 years ago
13

To determine whether they need to hire extra help for the holiday season, the managers of a railroad company want to estimate ho

w long, on average, it takes a crew to unload a freight car at the Lafayette station. They will calculate an estimator as the sample mean of a random sample of unloading times. The managers want the sample mean to have a standard error of 1.51.5 minutes. The corporate office has provided a standard deviation of 99 minutes to use for calculation purposes. How large should the random sample be to ensure the sample mean has the desired standard error?
Mathematics
1 answer:
nadezda [96]3 years ago
3 0

Answer:

36

Step-by-step explanation:

Data provided in the question:

Standard error = 1.5 minutes             ( ∵ number are repetitive 1.51.5 )  

Standard deviation = 9 minutes        ( ∵ number are repetitive 99 )

Now,

Standard error = ( Standard deviation ) ÷ √n

Here,

n is the sample size

Therefore,

on substituting the respective values, we get

1.5 = 9 ÷ √n

or

√n = 9 ÷ 1.5

or

√n = 6

or

n = 6² = 36

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earnstyle [38]

Answer:

c) y=16.57+1.83x

Step-by-step explanation:

Equation for regression line of y on x is given as

\hat{y}=mx+b --- (1)

where

\hat{y} = predicted value

m = slope of line

b = intercept

m and b are found as

m=r\frac{S_{y}}{S_{x}}---(2)\\\\b=\bar{y}-m\bar{x}---(3)

r = correlation coefficient = 0.88

Sx = standard deviation for independent variable x = 13

Sy = standard deviation for dependent variable y = 27

\bar{x} = mean value of independent variable x = 21

\bar{x} = mean value of dependent variable y = 55

Substituting these values in (2) and (3)

m=r\frac{S_{y}}{S_{x}}\\\\m=(0.88)\frac{27}{13}\\\\m=1.83

b=\bar{y}-m\bar{x}\\\\b=55-(1.827)(21)\\\\b=16.57

Putting these values of m and b in (1)

y=1.83x+16.57

5 0
2 years ago
Please help ASAP!!! Find the volume of the triangular prism.
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Answer:

96 cm³

Step-by-step explanation:

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2 years ago
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In a bag there are 10p coins, 20p coins and 50p coins
Scrat [10]

Answer:

Approximately 25p (please change to pounds by yourself I'm not European, sorry).

Ok so according to my research its 100 pence to one pound. Which will mean that 25p in pounds is £ 00.25

Step-by-step explanation:

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(Sorry I couldn't change to pounds)

And I tried to explain as much as possible, you can ask if you're confused.

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Reika [66]

Solve for w and l by using the system of equations.

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Substitute w+42 for l in the first equation.

2(w+42)=-2w+228

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Now substitute 36 for w in any equation to get l=78.

To graph the equations, first make them equal l.

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5 0
3 years ago
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notka56 [123]

Answer:

Step-by-step explanation:

4.5C

6 0
3 years ago
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