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lesya692 [45]
3 years ago
12

Find the 90% confidence interval for the standard deviation for the time it takes an inspector to check a bus for safety if a sa

mple of 27 buses has a standard deviation of 6.8 minutes. assume the variable is normally distributed.
Mathematics
1 answer:
Aleks04 [339]3 years ago
7 0
<span><span> - </span>Find the 90% confidence interval for the standard deviation for the time it takes aninspector to check a bus for safety if a sample of 27 buses has a standard deviation of 6.8 minutes.Assume the variable is normally distributed. ... Best Answer: Let X be the time it takes an inspector tocheck a bus n = 27</span><span>[PDF]<span>Setiio/t 7. </span></span>
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(34 points) URGENT !! A car rental company’s standard charge includes an initial fee plus an additional fee for each mile driven
sergeinik [125]
I just don’t know how much it would cost me a lot more to get a good one for it and it was so fun I love that too I think it’s a nice day for us but

5 0
2 years ago
A worker drags a box of mass 50 kg across a horizontal floor. The worker attaches a rope to the box and pulls on the rope so tha
Arlecino [84]

Answer:

A) F=\displaystyle{\frac{m(a+ \mu g)}{\cos(\alpha) -\mu \sin(\alpha)} }with a = \frac{2\Delta x}{t^2}

B) The magnitude of the pulling force is 24 % of the magnitude of the gravitational force acting on the box

Step-by-step explanation:

A) The forces acting on the box are the pulling force that the worker exerts on the rope, the friction, the normal force, and the gravitational force. See the attached diagram. Since the pulling force on the rope makes an angle with the horizontal, this will have components in the x and y-axis (see diagram).

In the y-axis, the box does not move, therefore:

\sum_{y} F = 0\\F\sin(\alpha) + N - F_g = 0\\N = F_g - F\sin(\alpha)\\N = mg - F\sin(\alpha) (1)

where \alpha is the given angle of the rope with the horizontal.

In the x-axis, the box moves with an acceleration a that can be calculated as a function of the given displacement and time interval as:

a = \frac{2\Delta x}{t^2} and the force equation is:

\sum_{x} F = ma\\F\cos(\alpha) -f =ma\\F\cos(\alpha) - \mu N = ma

now substituting N from equation (1):

F\cos(\alpha) - \mu N = ma\\F\cos(\alpha) - \mu (mg - F\sin(\alpha))=ma\\F\cos(\alpha) - \mu mg -\mu F\sin(\alpha)=ma\\F\cos(\alpha) -\mu F\sin(\alpha)=ma+ \mu mg\\F(\cos(\alpha) -\mu \sin(\alpha))=ma+ \mu mg\\\boxed{F=\frac{m(a+ \mu g)}{\cos(\alpha) -\mu \sin(\alpha)}}

and putting the expression for the acceleration:

\boxed{F=\frac{m \frac{2\Delta x}{t^2}+ \mu mg}{\cos(\alpha) -\mu \sin(\alpha)}} (2)

which is the requested expression

B) Substituting the values in (2) and using g=9.8\ \rm{ms^{-2}}:

F=\frac{50 \cdot ( 0.762939+ 0.1\cdot \cdot 9.8)}{\cos(36.8^{\circ}) -0.1 \sin(36.8^{\circ})}\\F=\frac{87.147}{0.740829} \\F=11.634\ \rm{N}

The gravitational force acting on the box is:

F_g=mg=50\cdot9.8=490\ \rm{N}

F/F_g = (117.634/490)\cdot 100 = 24 \%

Thus, the magnitude of the pulling force is 24 % of the magnitude of the gravitational force acting on the box.

8 0
4 years ago
Can someone help on this?
bezimeni [28]

Step-by-step explanation:

this just means that the first function with input value x = 0 is calculated. that result becomes the input value x for the second function. and that result becomes the input value x for the 3rd function. and that result is then our result.

to answer a and b we only need to look at the main operation of each function :

the first one uses only basic multiplication and subtraction.

the second one uses squaring.

the third one is a 1/x operation.

a.

since the final result is a negative number (-31), the second function with the square operation cannot be last.

because a square operation always delivers a positive result.

+a × +a = +a²

-a × -a = +a²

remember, for a square operation we multiply the same number by itself. therefore we cannot mix signs like -a × +a, because then they would not be the same numbers anymore.

b.

since the initial input value is 0, the third function (1/x) cannot be the first, because 1/0 is not defined.

c.

because of the "large" -32 term in the first function I guess that this will be the last one to create such a low negative result of -31.

since 1/x cannot be first, (x - 2)² is then first. that makes 1/x second, and (4x - 32) third, as mentioned.

let's try :

x = 0

(x - 2)² = (0 - 2)² = (-2)² = 4

x = 4

1/x = 1/4

x = 1/4

4x - 32 = 4×1/4 - 32 = 1 - 32 = -31

hurrah ! we are correct !

3 0
1 year ago
Explain why -4 is greater than -10 even though 4 is less than 10
Korvikt [17]
-4 is greater than - 10 because -4 is closer to 0 than -10 is
4 0
4 years ago
Read 2 more answers
Write the expression in standard form. 1/4 (4x+8)
slavikrds [6]
Here, 1/4 (4x + 8)

Apply the distributive property which tells: a(b + c) = ab + ac

= 4x/4 + 8/4

= x + 2   [ Final Answer ]

Hope this helps!
4 0
4 years ago
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