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sasho [114]
2 years ago
5

The lifetime for a certain type of tre has been shown to be five years the mean) with a standard deviation of 6 months. In a nor

mal distribution, what percentage of these tires will
last more than six years (more than two standard deviations above the mean)?
Mathematics
1 answer:
olga_2 [115]2 years ago
6 0

Answer:

2.28%

Step-by-step explanation:

mean = 5 years = 60 months

standard deviation = 6 months

X = number of years the tires will last

P = probability of ...

z = z-score

6 years = 72 months

z = (# of months - mean) / standard deviation

z = (72 - 60)/6

z = 12/6

z = 2

P(X > 72) = 1 - P(X < 72)

= 1 - P(z < 2)    

(using a Standard Normal Probabilities Table we can see that P(z < 2) = .9772)

So:

= 1 - .9772

= 0.0228 OR 2.28%

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Can u change order of operations ?
Anni [7]

Answer:

its best no to

Step-by-step explanation:

The only thing you can really change is switching subtraction and addiction, or division and multiplication. In the long run though its best just to say with the regural order and its earier later on.

please, (parentheses)

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7 0
3 years ago
Find the locus of a point such that the sum of its distance from the point ( 0 , 2 ) and ( 0 , -2 ) is 6.
jok3333 [9.3K]

Answer:

\displaystyle \frac{x^2}{5}+\frac{y^2}{9}=1

Step-by-step explanation:

We want to find the locus of a point such that the sum of the distance from any point P on the locus to (0, 2) and (0, -2) is 6.

First, we will need the distance formula, given by:

d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}

Let the point on the locus be P(x, y).

So, the distance from P to (0, 2) will be:

\begin{aligned} d_1&=\sqrt{(x-0)^2+(y-2)^2}\\\\ &=\sqrt{x^2+(y-2)^2}\end{aligned}

And, the distance from P to (0, -2) will be:

\displaystyle \begin{aligned} d_2&=\sqrt{(x-0)^2+(y-(-2))^2}\\\\ &=\sqrt{x^2+(y+2)^2}\end{aligned}

So sum of the two distances must be 6. Therefore:

d_1+d_2=6

Now, by substitution:

(\sqrt{x^2+(y-2)^2})+(\sqrt{x^2+(y+2)^2})=6

Simplify. We can subtract the second term from the left:

\sqrt{x^2+(y-2)^2}=6-\sqrt{x^2+(y+2)^2}

Square both sides:

(x^2+(y-2)^2)=36-12\sqrt{x^2+(y+2)^2}+(x^2+(y+2)^2)

We can cancel the x² terms and continue squaring:

y^2-4y+4=36-12\sqrt{x^2+(y+2)^2}+y^2+4y+4

We can cancel the y² and 4 from both sides. We can also subtract 4y from both sides. This leaves us with:

-8y=36-12\sqrt{x^2+(y+2)^2}

We can divide both sides by -4:

2y=-9+3\sqrt{x^2+(y+2)^2}

Adding 9 to both sides yields:

2y+9=3\sqrt{x^2+(y+2)^2}

And, we will square both sides one final time.

4y^2+36y+81=9(x^2+(y^2+4y+4))

Distribute:

4y^2+36y+81=9x^2+9y^2+36y+36

The 36y will cancel. So:

4y^2+81=9x^2+9y^2+36

Subtracting 4y² and 36 from both sides yields:

9x^2+5y^2=45

And dividing both sides by 45 produces:

\displaystyle \frac{x^2}{5}+\frac{y^2}{9}=1

Therefore, the equation for the locus of a point such that the sum of its distance to (0, 2) and (0, -2) is 6 is given by a vertical ellipse with a major axis length of 3 and a minor axis length of √5, centered on the origin.

5 0
2 years ago
Read 2 more answers
A certain virus is dying off at a rate of 18% per hour. Initially there were
djyliett [7]

Answer:

3 strain would still alive after 48 hours

Step-by-step explanation:

Initial population of virus = 40000 grams

A certain virus is dying off at a rate of 18% per hour.

We are supposed to find  how much of the  strain would still be alive after 48 hours

Formula : N(t)=N_0(1-r)^t

N_0=Initial population

N(t)= Population after t hours

r = rate of decrease = 18% = 0.18

t = time = 48 hours

So,the  strain would still be alive after 48 hours=40000(1-0.18)^{48}=2.91 \sim 3

Hence 3 strain would still alive after 48 hours

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3 years ago
A sector of a circle has a central angle measuring 80 degrees. If the area
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Answer:

675in

Step-by-step explanation:

not it

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2 years ago
Complete the statement with a situation and a unit of your choice. Then answer the question and draw a diagram.
yKpoI14uk [10]

Answer:

36/3=12x4=48

Step-by-step explanation:

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