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kotykmax [81]
4 years ago
8

Lifetime of a certain transistor in a certain application has a mean of 900 hours and a standard deviation of 30 hours. Four tra

nsistors are used, and the total length of time that the four resistors last is recorded. The transistors are independent of one another. What is the mean length of time in hours that the four transistors will last?
Mathematics
1 answer:
AURORKA [14]4 years ago
7 0

Answer:

3600 hours

Step-by-step explanation:

let total life time of t four transistors T = X1 + X2 + X3 + X4 (where X1,X2,X3 and X4 are life time of individual transistors

mean of the length of time that four transistors will last =E(T)=E(X1 + X2 + X3 + X4)

=E(x1) + E(x2) + E(x3) + E(x4) =900+900+900+900 =3600

and standard deviation of total time =SD(T)=sqrt(Var(T)) = sqrt(Var(X1) + Var(x2) + Var(x3) + Var(x4))

where sqrt means the square root

=sqrt(302+302+302+302) =sqrt(3600) =60

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Fractions im not too sure how to do this
steposvetlana [31]

Answer:

3 1/2 21/4

Step-by-step explanation:

3 1/2= 7/2= 7 divided by 2=

21/4=21 divided by 4=

\sqrt[4]{21}

4 goes into 21, five times which is 5 1/4

\sqrt[2]{7}

2 goes into 7, six times which is 6 1/2

Hope this helps you whith Fractions

5 0
4 years ago
Solve For X:<br><br>(-3/4)x - 9 = -27 <br><br>i need help asap.​
kakasveta [241]
For the question on the picture with -3/2 the answer is x=12, but the one you typed with -3/4 the answer is x=24
7 0
3 years ago
(Different one)<br><br> Factor 6x^2 - 10x - 4
Alina [70]
We can first factor all the terms by 2:
<span>6x^2 - 10x - 4=2(3x^2-5x-2)
</span>
Then we solve 3x^2-5x-2=0.

Discriminant : 25+4*3*2=49=7^2 hence the roots are (5-7)/6 and (5+7)/6 which are -1/3 and 2

Hence 3x^2-5x-2=(x-2)(3x+1)

Thus 6x^2-10x-4=2(x-2)(3x+1)
6 0
3 years ago
Read 2 more answers
In rectangle QRST, QS= 3x + 7 and RT= 5x - 3. Find the lengths or the diagonals of QRST
Marina CMI [18]

Answer:

The lengths of the diagonals is 22.

Step-by-step explanation: Since the shape is a rectangle, the diagonals are congruent, we can form the equation 3x+7=5x-3.

Solve for x; 2x=10-->x=5.

Plug 5 into one of the equations. 3(5)+7=22. 5(5)-3=22

Hope this helps!

:)

8 0
3 years ago
Please help me!!!!!!!
lawyer [7]

Answer:

  • f(x)=\sqrt{x+3}
  • f(x)=\dfrac{1}{(x-2)(x-4)}

Step-by-step explanation:

a) It can be convenient to use the square root function as one being defined only for values greater than or equal to some number. Here, we need to shift that function 3 units to the left, so its domain is [-3, ∞).

  f(x)=\sqrt{x+3}

__

b) One way to put holes in a function is to put vertical asymptotes there. This function can be defined to have vertical asymptotes at x=2 and x=4 so those values are excluded from the domain.

  f(x)=\dfrac{1}{(x-2)(x-4)}

3 0
3 years ago
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