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Morgarella [4.7K]
3 years ago
14

A device that continuously measures and records seismic activity is placed in a remote region. The time, T, to failure of this d

evice is exponentially distributed with mean 3 years. Since the device will not be monitored during its first two years of service, the time to discovery of its failure is X = max(T, 2).
Mathematics
1 answer:
Allisa [31]3 years ago
5 0

Answer:

E[X]= 2 + 3 e^{(-2/3)

Step-by-step explanation:

The objective of this question is to determine E[X].

T is defined (0,infinity)

X=max(c,T)

where; c=constant

E[X]=c+function (c,infinity) Sf(t)dt

E[X] =e^{-t/3

E[X]=2+function (2,infinity)e^{-t/3dt

E[X] =(2+e^{-t/3})/(1/3) function (2,infinity)

E[X]= 2 + 3 e^{(-2/3)

If X = T   if T ≥ 2 and X = 2    if 0 ≤ T < 2,

So Since T is  exponentially distributed with mean 3,  the density function of T is  f(t) = (1/3)e^{(-t/3)

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Lilit [14]

Answer:

1. -13

2. 8

Step-by-step explanation:

39 / -13 = 3

-64 / 8 = -8

Hope this helps!!!

3 0
3 years ago
The set notation of the counting numbers
boyakko [2]
Basically, he said that anything with a collection of objects is a set. Having said that, we felt afterward that we could easily make up our own sets.

You could be surprised what a set could be made of. Basically, any collections of things that make sense.

Examples of sets:

1. 

<span>The set of all letters in the modern English alphabet </span>

<span>What is included in that set? a, b, c, d, e, f, etc... </span>

2. 

The set of all great mathematicians in the past

What is included in that set? We could mention with Carl Gauss, Isaac Newton, Einstein, Blaise Pascal, Euclid, Pierre de Fermat, etc..Sorry, I am not silly to list them all here!

3. 

The set of all positive numbers less than 10

What is included in that set? 1, 2, 3, 4, 5, 6, 7, 8, 9

4. 

The set of all types of sausages

What is included in that set? I am not sure I am knowledgeable enough in this area. I know Italian sausage and ???. What else? Did I miss something?

5. 

The set of all states in the United States

Oh Boy.Geography! You know what.I think you got the point. Let us move on to something else

Finite and infinite set:

A set is finite if you can list all its elements and infinite otherwise.

All sets described above are finite because you can list or count all their elements

However, among the five sets, one set can be turned into an infinite set with one small change. That set is set number 3

If I get rid of the word positive and say instead "the set of all numbers less than 10" the set in now infinite because you cannot count all those numbers less than 10.

Ways to define a set:

a. With a verbal description: All sets above are described verbally when we say, " The set of all bla bla bla "

<span>b. A listing of all members separated by commas with braces ({ and }): </span>

A listing of set 1 is written as: {a, b,c,d,e,f,....,z}

c. Set-builder notation:

Set 1 and set 4 can be written as { x / x is a letter of the modern English alphabet} and { x / x is a type of sausage}

{ x / x is a letter of the modern English alphabet} is read, " The set of all x such that x is a letter in the modern English alphabet

Set-builder is an important concept in set notation. You must understand it.

We use capital letters such as A, B, and so forth to denote sets

For example, you could let A be the set of all positive numbers less than 10.

<span>We use the symbol </span>Î<span> to indicate that an object belongs to a set and the symbol </span>Ï<span> to indicate that an object does not belong to a set</span>

For example, if A is the set of all positive numbers less than 10, then 2 ∈ A, but 12 ∉ A

<span>A set that has no element is called </span>empty set<span> and is denoted by { } or ∅ </span>

For example, {x / x is a human being who have lived 10,000 years} is an empty set because it is impossible to find at least one human being who have lived so long

Two sets are equal if they have exactly the same element

For example, { x / x is a number between bigger than 1 and less than 5} and { 2, 3, 4} are equal sets

Subtleties with set notation:

Two sets are still equal even if the same element is listed twice

{ 2, 3, 4} and { 2, 3, 3, 4} are equal

The order of elements in sets does not matter

{ 2, 3, 4} = { 2, 3, 3, 4} = { 4, 3, 2}

3 0
3 years ago
When you multiply (3+6i)(3+7i) you get an answer of the form a+bi. Find a.
stiks02 [169]

(3 + 6i)(3 + 7i)

FOIL: First, Outside, Inside, and Last

3 x 3 = 9

3 x 7i = 21i

6i x 3 = 18i

6i x 71= 42i

9 + 21I + 18I + 42I = 9 + 81I

a = 9

B = 81I

5 0
3 years ago
What is the unit rate of 36 gal in 12 min
Vesna [10]
To find how many gallons in 12 min,
 
36         ?
---- =   -----
12         1
Cross multiply

36x1=36

12x?=36

36/12=3

The unit rate is 3 gallons in 1 minute.

I hope I helped!
7 0
3 years ago
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Ksju [112]

Answer:

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Step-by-step explanation:

the ending of "6" is forever.

7 0
3 years ago
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