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iris [78.8K]
2 years ago
6

The length of time Y necessary to complete a key operation in the construction of houses has an exponential distribution with me

an 18 hours. The formula C = 100 + 60Y + 3Y2 relates the cost C of completing this operation to the square of the time to completion. The mean of C was found to be found to be 3,124 hours and the variance of C was found to be 28,460,160. How many standard deviations above the mean is 4,000 hours? (Round your answer to two decimal places.)
Mathematics
1 answer:
Butoxors [25]2 years ago
4 0

Answer:

0.16

Step-by-step explanation:

Given that the length of time Y necessary to complete a key operation in the construction of houses has an exponential distribution with mean 18 hours.

The formula for cost of completing this operation is

C = 100 + 60Y + 3Y^2

C has mean 3124

Var(C) = 28,460,160

Std dev (C) = \sqrt{28460160} \\=5334.81

X = 4000 hours

Difference = 4000-3124 = 876

Mean diff/std dev = \frac{876}{5334.81} \\=0.164

i.e.nearly 0.16  standard deviations above the mean is 4,000 hours

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The heat developed in an electric wire varies jointly as the wires resistance, the time the current flows, & the square of t
never [62]

Answer:

4 ohms

Step-by-step explanation:

The question is "In two minutes a current of 5 amps develops 1,200 heat units in a wire of 8 ohms resistance. What resistance does a similar wire have, which develops 6,000 heat units with a current of 10 amps in 5 minutes?"

Current, I₁ = 5 A

Heat, Q₁ = 1200 units

Resistance, R₁ = 8 ohms

Time, t₁ = 2 min = 120 s

New heat, Q₂ = 6000 units

Current, I₂ = 10 A

New time, t₂ = 5 min = 300 s

We need to find the new resistance.

Heat developed is given by :

Q=I^2Rt

\dfrac{Q_1}{I_1^2R_1t_1}=\dfrac{Q_2}{I_2^2R_2t_2}\\\\R_2=\dfrac{Q_2\times I_1^2R_1t_1}{Q_1I_2^2t_2}\\\\R_2=\dfrac{6000\times 5^2\times 8\times 120}{1200\times 10^2\times 300}\\\\=4\ \Omega

So, the new resistance is 4 ohms.

5 0
2 years ago
In triangle RG shown below. m 63 and m 30 Which of the following is the<br> 63
Tatiana [17]

Answer:

The value of the hypotenuse is 69.77 meters.

Step-by-step explanation:

To determine, in triangle RG, the value of its hypotenuse if its sides measure 63 meters and 30 meters, the following calculation must be performed, applying the Pythagorean theorem:

63 ^ 2 + 30 ^ 2 = X ^ 2

3969 + 900 = X ^ 2

√ 4869 = X

69.77 = X

Therefore, the value of the hypotenuse is 69.77 meters.

7 0
3 years ago
2343443444<br> Is it rational or irrational?
finlep [7]

Answer:rational

Step-by-step explanation:

7 0
3 years ago
Read 2 more answers
Is x = -7, the solution to -11 + 2x = -26? Justify your answer in complete sentences.
Natali5045456 [20]
First of all, you can move the +2x to the other side:
-11 = -26 - 2x

Then you can move the -26 to the other side and then simplify:
-11+26 = -2x
 15 = -2x

Then you can divide both sides by 2:
7.5 = -x

Then you can flip the sides and the signs around:
x = -7.5

No, The answer is not -7, it is -7.5
Hope this helps! :)
4 0
2 years ago
Ok ik that I do math for ppl a lot but if someone could plz just help me with theses math problems (if u say that u will help I’
hodyreva [135]
I will help you with your problem
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2 years ago
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