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Alex Ar [27]
3 years ago
8

Suppose that you arrive at a bus stop randomly, so all arrival times are equally likely. The bus arrives regularly every 30 minu

tes without delay (say, on the hour and on the half hour). What is the expected value of your waiting time? Explain how you got your answer.
Mathematics
1 answer:
Semmy [17]3 years ago
7 0

Answer:

E(x) = 15 minutes

Step-by-step explanation:

The random variable X (waiting time)  has a uniform distribution between the interval [0,30], because it is just as likely that you arrive in any time and then your waiting time is minimum 0 minutes and maximum 30 minutes

The expected value  of a random variable uniform is:

E(x) = \frac{a+b}{2}

      Where a and b are the interval's extremes

Thus

E(x) = \frac{0+30}{2}

E(x) = 15 minutes

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Someone please help or i’ll be failing geometry this year
Vlad [161]

Step-by-step explanation:

I don't know what constructions you were taught.

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by saying 1:2 she means the second triangle should have sides with twice the lengths of the first triangle (f=2).

and the extra challenge - same basic thing. she allows you to pick one of the two triangles as reference. and then you need to draw a third triangle (again with the same angles) with the side lengths extended by the scaling factor f of 4/3.

I would draw the triangles right on top of each other with the same starting corner (let's call it A) for all 3.

we would get the triangles ABC, AMN and AXY.

the points B and C would be then halfway on AM and AN.

and M and N would then a bit before X and Y on AX and AY.

the beauty is, you only need to construct 2 sides of every new triangle down to the new endpoints. the third side is automatically scaled correctly, and you only need to connect these new endpoints.

let's assume you draw a triangle (just very simple) ABC with all side lengths being 3. so, AB=3, AC=3, BC=3.

now you draw AMN by extending AB and AC to a side length of 6 (f=2) creating M and N, and you connect M and N.

and then you can create the third triangle AXY by extending AM and AN by a factor of 4/3 to side lengths of 8 (4/3 × 6 = 8) creating new end points X and Y. and you connect X and Y.

and that is it. all 3 triangles are similar (the same angles), and all sides of a triangle have the same length ratio to the sides of the other triangle(s).

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3 years ago
The mean of a normally distributed dataset is 12, and the standard deviation is 2.
Schach [20]
So lets do it like this:
z = (X-Mean)/SD 
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<span>z2 = (16-12)/2 = + 2 </span>
<span>According to the Empirical Rule 68-95-99.7 </span>
<span>Mean more or less 2SD covers 95% of the values </span>
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3 years ago
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Jlenok [28]

Answer:

1 Original amount: 20

End amount: 15

<h3>(20 - 15)/20 x 100 = (5/20) x 100 = 25% decrease</h3>

2 Original amount: 30

End amount: 45

<h3>(45 - 30)/30 x 100 = (15/30) x 100 = 50% increase </h3>

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<h3>550/625 =550 ÷ 625 =0.88</h3><h3>0.88 =0.88 × 100/100 =(0.88 × 100)/100 =88/100 =88% decrease</h3>

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5 Original amount: 165

End amount: 222.75

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End amount: 38.61

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ratelena [41]

Answer: 637

Step-by-step explanation:

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2 years ago
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