The local authorities in a certain city install 10,000 electric lamps in the streets of the city. If these lamps have an average life of 1000 burning hours with a standard deviation of 200 hours, assuming normal distribution, what number of lights might expected

Answers

Answer 1

Step-by-step explanation:

It is given:

[tex]\mu=1000[/tex], [tex]\sigma=200[/tex]

Let x be the random variable that denotes the number of hours the lamp lights up.

what number of lights might expected to fail in the first 800 burning hours

Answer: We are required to find the expected number of lights to fail in the first 800 burning hours.

First, we have to find the probability as:

P(Z < 800)

Using the z-score formula, we have:

Using the z-score formula, we have:

[tex]P(x <800)=P \left(z<\frac{800-1000}{200} \right )[/tex]

=P(z<-1)

Now using the standard normal table, we have:

P(x<800)=P(z<-1)=0.1587

Therefore, the expected number of lights to fail in the first 800 burning hours is:

[tex]\boldsymbol{0.1587 \times 10000=1587}[/tex]

After how many burning hours 10% of the lamps would be still burning?

We first need to find the z-value corresponding to area = 1- 0.10 = 0.90. Using the standard normal table, we have:

z(0.90)=1.28

Now using the z-score formula, we have:

[tex]z= \frac{x-\mu}{\sigma}[/tex]

[tex]1.28= \frac{x-1000}{200}[/tex]

[tex]1.28 \times 200= x-1000[/tex]

[tex]256= x-1000[/tex]

x= 1000+256

[tex]\boldsymbol{x= 1256 }[/tex]

Answer 2

Using the Zscore principle, the number of bulbs expected to Fail in the first 800 burning hours is 1587

Given the Parameters :

σ = 200μ = 1000x = 800

The number of Lamps that might be expected to fail in the first 800 burning hours :

Recall:

Zscore = (x - μ) ÷ σ

Zscore = (800 - 1000) / 200 = -1

Using the normal distribution table :

P(Z < -1) = 0.15866

The number of bulbs expected to fail :

P × total number of bulbs

0.15866 × 10000 = 1586.6

Hence, 1587 bulbs are expected to fail in the first 800 burning hours.

Learn more : https://brainly.com/question/25226377


Related Questions

PLEAS PLEAS PLEAS HELP ME!!!!!!!!!!!!!!!

The Garcias are on their way to the beach. They are traveling at
a rate of 30 miles per hour. Use the ordered pairs to graph the
distance traveled over time.

Answers

Answer:

draw a line for the plotted points and put an arrow at the end, see my answer

Step-by-step explanation:

please click the heart button to give thanks for my work! :)

In an animal shelter, the ratio of dogs to cats is 5 to 3. There are 25 dogs. Write and solve a proportion to find the number of cats.
Ο 18
Ο 21
Ο Ο Ο Ο
Ο 15
Ο 16

Answers

I would say c (15)
Have a good day!

Answer:

15 cats

proportion 3x : 5x

in this case x= 5

Step-by-step explanation:

divide 25 by 5

=5

now you know the factor is 5

multiple 3 by 5

=15

The temperature is 15º and is expected to fall 2º each hour during the night. write the linear equation

Answers

Answer:

y = 15 - 2x

Step-by-step explanation:

The starting temp is 15, and we expect it to fall 2 degrees each night. We substitute x and y, y = total temp at the end of the examined time period, x = number of hours.

Please give me thanks by clicking the heart button! :)

Answer:

15 - 2(x)

x = hours

Step-by-step explanation:

I need help please I have to finish this

Answers

Answer:

We want to get y and x such that it satisfices all geometric relations:

3y=87

y=87/3 = 29 degree

Hence y= 29 degree

Two parallel lines tell us that 87=3x such that x=29

Step-by-step explanation:

1. Change the following into 12 hour clock time
a) 1720 hours. b)0235 hours​

Answers

Answer:

A) 5:20 pm

B) 2:35 am

Step-by-step explanation:

The hours in am are from 00:00 - 12:00, the numbers after 12 for example 17, you subtract 12 and the remaining is the hours and what is left of the number for example 20 is the minutes.

I am horrible at explaining but I hope this helps...  :)

Answer:

a) 5:20

b) 2:35

Step-by-step explanation:

a) Subtract 12 from the 17 at the beginning of 1720, leaving you with 5. This is the hour component of standard time, and will be placed on the left side of the colon (5:__). Then, put  the last two digits onto the other side of the colon in standard time like so: 5:20.

b) For this one, because the first two digits don't exceed twelve, you simply have to divide the first two digits from the last two digits and put a colon between them: 02:35, or 2:35.

There are 60 seconds in a minute use a tape diagram to find the total number of seconds in 5 minutes and 45 seconds

Answers

60 x 5 + 45 = 345 Seconds

The answer is 345 seconds I hope it helped


6. An ice cream costs 15 more than a cold drink. If the cost of
buying 5 ice creams is 125, find the price of a cold drink.

Answers

Answer:

The price of a cold drink is 10 dollars.

Step-by-step explanation:

We can use proportion.

[tex] \frac{5 \: ice \: creams}{125 \: dollars} = \frac{1 \: ice \: cream}{x} \\ \\ \frac{5x}{5} = \frac{125}{5} \\ \\ x = 25[/tex]

So we found out that one ice-cream costs $25.00.

The statement said, "An ice cream costs 15 more than a cold drink"

In other words, A cold drink costs 15 dollars less than an ice cream.

So we would subtract.

[tex]25 - 15 = 10[/tex]

So a cold drink costs $10.00.

10.00 dollars is the answer

Paul paid $7 per hour to rent a bicycle. Wilson paid $9 per hour to rent a bicycle. If they both rent bicycles for 3 hours, how much MORE will Wilson pay?

Answers

Answer:

6

Step-by-step explanation:

The difference in cost / hour = 9 - 7

9 - 7 = 2

They both take the bikes for 3 hours.

Difference * time = 2 * 3 = 6 dollars

Wilson pays 6 dollars more.

Answer:

,$48

Step-by-step explanation:

7×3=21

9×3=27

27-21=6

I need the answer ASAP! Please help me!

Answers

Answer:

Please check the explanation.

Step-by-step explanation:

Determining the length of BC

From the diagram, it is clear that

The point B is located at (-8, 10) and point C is located at (8, 10)

Since points A and C are located on a horizontal straight line. Thus, the length of BC can be determined by counting the x-axis units from reaching x = -8 to x = 8. i.e. 8-(-8) = 8+8 = 16

Thus, the length of BC = 16 units

Determining the length of CD

Given

C (8, 10) D (2, -2)

The distance between C(8, 10) and D(2, -2)

[tex]\mathrm{Compute\:the\:distance\:between\:}\left(x_1,\:y_1\right),\:\left(x_2,\:y_2\right):\quad \sqrt{\left(x_2-x_1\right)^2+\left(y_2-y_1\right)^2}[/tex]

[tex]CD=\sqrt{\left(2-8\right)^2+\left(-2-10\right)^2}[/tex]

      [tex]=\sqrt{6^2+12^2}[/tex]

      [tex]=\sqrt{36+144}[/tex]

      [tex]=\sqrt{180}[/tex]

      [tex]=\sqrt{36\times 5}[/tex]

      [tex]=6\sqrt{5}[/tex]

Thus, the length of CD [tex]=6\sqrt{5}[/tex] units

Determining the length of ED

Given

E (-8, -4) D (2, -2)

The distance between E(-8, -4) and D(2, -2)

[tex]ED=\sqrt{\left(2-\left(-8\right)\right)^2+\left(-2-\left(-4\right)\right)^2}[/tex]

      [tex]=\sqrt{10^2+2^2}[/tex]

      [tex]=\sqrt{100+4}[/tex]

      [tex]=\sqrt{104}[/tex]

       [tex]=\sqrt{26\times \:4}[/tex]

        [tex]=2\sqrt{26}[/tex]

Thus, the length of ED [tex]=2\sqrt{26}[/tex] units

Determining the length of EB

From the diagram, it is clear that

The point E is located at (-8, -4) and the point B is located at (-8, 10)

Since points E and B are located on a vertical straight line. Thus, the length of EB can be determined by counting the y-axis units from reaching y = -4 to y = 10. i.e. 10-(-4) = 10+4 = 14

Thus, the length of EB = 14 units

Amplitude: 6 Period: 44
Phase shift:

Answers

I don’t understand, sorry I need more context lol

Step-by-step explanation:

provide more details, please

Martina used 3/4 of a bottle of conditioner in 7/12 of a year. How much conditioner would she use in a full year

Answers

Step-by-step explanation:

7 months = 3/4

1 month = 3/4 ÷ 7

= 3/28

12 months / 1 year = 3/28 x 12

= 9/7

not sure if its correct

Answer: 1 2/7

trust me it just worked for me on IXL

What is the magnitude of the vector shown?
5
13
radical 5
radical 13

Answers

Answer:

D on edge

Step-by-step explanation:

radical 13

PLEASE HELP!!!!!!
Solve the following system of equations using elimination.
5x+y=24
-5x-4y=-56

Answers

Answer:

x = 8/3 and y = 32/3

Step-by-step explanation:

Add the two equations, getting -3y = -32, thus y = 32/3

Sub for y in first equation, getting 5x + 32/3 = 24

5x = 40/3

x = 8/3

Is it SSS or SAS. Please helpp

Answers

I always had trouble with these too.

The correct answer is: SSS

Terri spent $4.75 on candy,
$1 on soda, and $8.20 on a
ticket. If Terri paid with a
$20 bill, how much money
did she have left

Answers

Answer:

Step-by-step explanation:

$4.75+1+$8.20= $13.95

$20.00 - $13.95 = $6.05

Answer:

$6.05

Step-by-step explanation:

candy - $4.75

soda - $1

ticket - $8.20

4.75 + 1 + 8.20

$13.95

bill - $20

20 - 13.95

$6.05

Pleaseeee help me I need help reallly bad

Answers

Answer: 9. Matches with 1

10. Matches with 5

11. Matches with 64

12. Matches with 32

Explanation:

9. Insert the numbers that equal the variables from the top of the page.

7-3/4 = 1

10. 3^2 - 2^2

9 - 4 = 5

11. 4(8)(2) = 64

12. (8)^2 - 4(4)(2)
64 - 32 = 32

PLEASE HELPPPPPPPPP! 44 POINTS

Answers

Answer:

#6-

1. 9x30=(9x10)+(9x10)+(9x10)

2. 9x30=9(10+10+10)

3. 9x30=270

#7-

1. 7x50=7x(10+10+10+10+10)

2. 7x50=7x(25+25)

3. 7x50=350

#8-

1. 2x90=(2x45)+(2x45)

2. 2x90=90+90

3. 2x90=180

Step-by-step explanation:

Hope this helps!

What is the reason for each step in the solution of the inequality?
700 + 16 < -5(4 – 5x)
Match the reason with the correct step in the inequality.

Answers

I think it is givin. But I’m am not 100% sure

The happy apple farm has 560 apple trees. Each apple tree has 169 apples. How many apples are on all the trees together?

Answers

Answer:94,

Step-by-step explanation:

There are 94,640 apples on all the trees together. Because since each apple tree has 169 apples, and there are 560 apple trees, 560 times 169 = 94,640. I hope this helps! :)

IT WUU Tate for school on a
Given that 35.5% of them were men, 40% of them were women and the rest were
OXFORD
particular day, find the number of students who were punctual for school.
1800 people attended the National Day dinner in a certain constituency.
children, find the number of children who attended the dinner.​

Answers

Answer:

Number of students = 441 Students

Step-by-step explanation:

Given:

Percent of women = 40%

Percent of women = 35.5%

Total number of people = 1,800

Find:

Number of students

Computation:

Percent of student = 100% - 35.5% - 40%

Percent of student = 24.5%

Number of students = 1,800 x Percent of student

Number of students = 1,800 x 24.5%

Number of students = 441 Students

Please help answer the first 5 boxes for brainslt

> for brainslt

Answers

Step-by-step explanation:

5 points is too small for this..

PLEASE HELP!

Find the real or imaginary solutions of the following equation by factoring.

y^3 + 27 = 0

Answers

Answer:

-31.5(1 + i√3)1.5(1 - i√3)

Step-by-step explanation:

y³ + 27 = 0(y + 3)(y² - 3y + 9) = 0

1. y + 3 = 0 ⇒

y = -3

2. y² - 3y + 9 = 0

y = (3 ±√(3² -4*9))/2y = (3 ± √-27)/2y = (3 ± i√27)/2y = 3/2(1 ± i√3)y = 1.5(1 ± i√3)

Answer:

Do u still need the answer?

Step-by-step explanation:

Find the it out 12 divided by 3/5. 12 divided by 2/25. 8divided by 1/7. 12divided by 1/5

Answers

Answer:

Step-by-step explanation:

1. 20

2. 150

3. 56

4. 60

hope this helps. i am in algebra two so you can trust my answers. happy holidays and stay safe

Determine if the correlation between the two given variables is likely to be positive or negative, or if they are not likely to display a linear relationship. The retail price of a particular smartphone and the number of units sold at that price

Answers

Answer:

no correlation

Step-by-step explanation:

The price of the smartphone is fixed beforehand, therefore price does not depend upon the number of units sold.

Hence, there is no correlation between the two given variables.

Hence, no correlation would be the answer.

Which expression is represented by the set of algebra tiles below?
O x+6
O x-6
O 6-X
O 6x- 1

Answers

Answer:

The answer is B

Step-by-step explanation:

Lol I just had this same question on edge 2021 (◕‿◕✿)

Answer:

It Is B, x-6.

Step-by-step explanation:

I Just Did The Unit Test Review (ノ◕ヮ◕)ノ*.✧

simplify the expression

4.2v - 5 -6.5v =​

Answers

Answer:

-5 - 2.3v

Step-by-step explanation:

You want to combine like terms and since two of the numbers have variables, then you can add them both together

4.2v - 6.5 v = -2.3 v

So... -5 - 2.3v or

-2.3v - 5

either or there both same

Hope this helped!

Mrs. Browning bought ice cream treats for 6 children. Each child picked either a sundae or a milkshake. The sundaes cost $2 each and the milkshakes cost $5 each. If Mrs. Browning spent a total of $21, how many of each type of treat did she buy?


Please help me please !!!

Answers

Answer:

3 milkshakes and 3 sundaes

Step-by-step explanation:

3 * 5 = $15 + 3 * 2 = $21

Yes the person on top right. 5x3= 15 and 6x3=6. 15+6 =21 so 21 dollars

Marc wants to know if the mean age of the prison population in his city is less than 26 years. He obtains a random sample of 25 prisoners, and finds a mean age of 24.4 years and a standard deviation of 9.2 years. Ata significance level of 0.05, what is his conclusion?​

Answers

Answer:

gsgsbsbsbs

Step-by-step explanation:

yewhsgshdhhssjbs

16y5+4y5-12y3+15y3?
What is the simplified form?

Answers

Answer:

[tex]20y^5+3y^3[/tex]

Step-by-step explanation:

[tex]16y^5 + 4y^5 -12y^3 + 15y^3[/tex]

All we can do here is combine like terms (add those that have the same the same exponent)

[tex]20y^5+3y^3[/tex]

Good luck!

Answer:

[tex]20y^{5} +3y^{3}[/tex]

Step-by-step explanation:

[tex]16y^{5} +4y^{5} =20y^{5}[/tex] and [tex]-12y^{3} +15y^{3} =3y^{3}[/tex]

So [tex]20y^{5} +3y^{3}[/tex]

Find the perimeter of image below. 42 square units, 52 square units, 56 square units, 44 square units

Answers

Answer:

194 square units

Step-by-step explanation:

perimeter is the measurement of the distance surrounding a shape. There fore, the perimeter of the shape is: 42+53+56+44=194 square units

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