Suppose that the lifetimes of a certain kind of light bulb are normally distributed with a standard deviation if 110 hours. If exactly 95% of the bulbs die before 920 hours, find the mean lifetime if the bulbs

Answers

Answer 1

Answer:

The mean life time of the bulbs is approximately 739 hours

Step-by-step explanation:

Here, we want to calculate the mean life time

From the question, 95% of the bulbs die before 920 hours

What this mean is that the probability that a bulb will die before 920 hours is 95% = 95/100 = 0.95

Now, we need the z-score that is exactly equal to this value

Using the standard normal distribution table, the z-score corresponding to this probability value is 1.645

Mathematically;

z-score = (x-mean)/SD

In this case, x is 920, SD is standard deviation which is 920 hours

thus, we have it that;

1.645 = (920-mean)/110

110(1.645) = 920 - mean

180.95 = 920 - mean

mean = 920- 180.95

mean = 739.05


Related Questions

Two airplanes leave the same airport. One heads north, and the other heads east. After some time, the northbound airplane has traveled 68 miles. If the two airplanes are 85 miles apart, how far has the eastbound airplane traveled?

Answers

Answer:

17 miles

Step-by-step explanation:

85 - 68

17

Find the rate change

Answers

Rate change is $3.50

answer the question for 10 points and brainilest

Answers

Answer:

The one at the bottom left. C

Step-by-step explanation:

Your company plans to invest in a particular project. There is a 35% chance that you will lose $30,000, a 40% chance that you will break even, and a 25% chance that you will make $55,000. Based solely on this information, what should you do?

Answers

Based on the information I think you should not invest in the project. The chances of losing money or not making any money is much higher then the chances of making money

Consider the system of equations.


3x − y = 5,

2x + 3y = −15


Which value can the first equation be multiplied by to form opposite values on the y-term? A=-3 B= -2 C=2 D=3

The solution to the system of equations is .A= (-5,0) B= (5,0) C= (0,-5) D=(0,5)

Answers

Answer:

D and C

Step-by-step explanation:

Given the 2 equations

3x - y = 5 → (1)

2x + 3y = - 15 → (2)

Multiplying (1) by 3 and adding to (2) will eliminate the y- term

9x - 3y = 15 → (3)

Add (2) and (3) term by term to eliminate y

11x + 0 = 0

11x = 0 ⇒ x = 0

Substitute x = 0 into either of the 2 equations and solve for y

Substituting into (2)

2(0) + 3y = - 15

0 + 3y = - 15

3y = - 15 ( divide both sides by 3 )

y = - 5

solution is (0, - 5 )

Answer:

d and c my guy

Step-by-step explanation:

just did it

I really need someone’s help I don’t remember how to do this

Answers

Answer:

3

Step-by-step explanation:

cubed root means _x_x_= the number

so in this case it would be _x_x_=27

and what times what times what equals 27?

3x3x3=27

A Choir director made a histogram showing his ages of the members in choir which statement about the data in the histogram must be true

Answers

Answer:

C) The choir has a total of 100 members

Step-by-step explanation:

Histogram is the graphical representation of data with the use of bars of different heights.

From the histogram attached:

A) Number of people fro 46 to 73 years = 30 + 5 + 15 = 50

Total Number of people = 15 + 20 + 5 + 10 + 30 + 5 + 15 = 100

Therefore half of the people are from 46 to 73 years.

Therefore the statement that more than half of the people are from 46 to 73 years is wrong.

B) The histogram shows the number of members between each age range, it does not show the number of male and female members. Hence we cannot determine the number of male and female members.

C) Total Number of people = 15 + 20 + 5 + 10 + 30 + 5 + 15 = 100

The choir has a total of 100 members

D) Number of people less than 32 years = 15 + 20 = 35

Therefore the statement that exactly 20 members are less than 32 years is wrong

can someone help me with this please^

Answers

Answer:

a) 126degrees

b) 47degrees

Step-by-step explanation:

The sum of two supplementary angles is 180 degrees.

Let the other angle be x

x  + 54 = 180

x = 180 - 54

x = 126degrees

The supplement is 126degrees

b) The sum of two complementary angles is 90 degrees.

Let the other angle be y

y  + 43 = 90

y = 90 - 43

y = 47degrees

Hence the complement is 47 degrees

Find the volume of a cone that has a radius of 14ft and a height of 18.9ft

Answers

Answer:

[tex]v = \pi {r}^{2} \frac{h}{3} = 14 \times 14 \times 3.14 \times \frac{18.9}{3} = 3877.272[/tex]

WILL MAKE BRAINLIST only if you solve this

Answers

Answer:

18/18 is fractions

16/16 is fractions

Step-by-step explanation:

18/18x16/16=1

Theres your answer.

evaluate show the solution of 14C6 and 15C4​

Answers

Answer:

Evaluate each expression for a = 4, b = 2, and c = 5.

c − a

d. You can multiply cand 8
by in 1(c + 8) to find
an equivalent expression. True
False

Answers

Answer:

i don't think you can (but i could be wrong)

Step-by-step explanation:

my thinking is that since there is still an unknown variable even after you've multiplied that there can't be an equivalent expression

1(c+8)*8

=?

good luck :)

i hope this helps

**please let me know if this was incorrect**

have a nice day!

Find the value of x and classify the triangle plzzz

Answers

Answer:

x=24°

The triangle is an obtuse isosceles triangle

Step-by-step explanation:

This is an obtuse isosceles triangle because it has two congruent sides, making it an isosceles triangle, and there is an obtuse angle, which is any angle greater than 90°.

The interior angles of a triangle add up to 180, so let's make an equation.

132+2x=180

Then solve for x

subtract 132 from both sides

2x=48

Divide by 2 on both sides

x=24

The answer would be X=24 obtuse isosceles triangle

Help
Mr. McGill is solving the following problem: 42x=163. Mr. McGill set 2x=3 and got x=32 as his answer. Tell the mistake Mr. McGill made and tell the correct answer.

Answers

Answer:

The mistake McGill made was to eliminate 4 and 16 from both sides before solving fro x

Step-by-step explanation:

Given the expression

42x = 163

To get the values of x, we are to divide both sides by the coefficient of x i.e 42 as shown;

42x = 163

42x/42 = 163/42

x = 163/42

x = 3.88

Hence the mistake McGill made was to eliminate 4 and 16 from both sides before solving fro x

The graph shows a line and two similar triangles which expression finds the equation of the line?

Answers

Answer:c

Step-by-step explanation:

Answer:

hello, sorry i'm late, your answer would be: option b, y/x = 2/3

Step-by-step explanation:

proof:

Find the volume of a sphere with a surface area of 1296 in.

Answers

Answer:

V≈4387.14

Step-by-step explanation:

The equation for the speed/distance
of a tornado is s = 93 log(d) + 65.
If the speed is 190 mph, what is the distance?

Answers

Step-by-step explanation:

S = 93 log (d) + 65; S = wind speed; d = distance traveled by tornado

A) tornado travels 130 miles = d; find S

S = 93 log10(130) + 65

S = 261.6 mph rounds up to 262 mph

Answer:

22 miles

Step-by-step explanation:

s = 93 log(d) + 65  and  s = 19093 log(d) + 65 = 19093 log(d) = 125log (d) = 125/93log (d) = 1.344 (rounded)d = 10^1.344d = 22 miles (rounded)

The right rectangular prism below is made up of 8 cubes. Each cube has an edge length of 12 inch.

Answers

Answer:

1 in³

Step-by-step explanation:

Complete question

The right rectangular prism below is made up of 8 cubes each cube has an edge length of 1/2 inch what is the volume of this prism

Volume of a cube = l³

If each cube has an edge length of 1/2 inch, then:

Volume of each cube = 1/2³

Volume of each cube = 1/8

Volume of the prism = 8×1/8

Volume of the prism = 1 in³

Consider the ready-made tent with flooring included that is shown in de diagram below.

What is the least amount of fabric needed to make the four-foot high tent?

Answers

Answer:

136 ft²

Step-by-step explanation:

Total surface area is the amount of fabric:

S = 2(1/2*6*4) + 2(7*5) + (7*6) = 136 ft²

1. Use the given key to answer the questions.
0.1
tenth
0.01
hundredth
0.001
thousandth
0.0001
ten-thousandth
a.
What number does this diagram represent?
b. Draw a diagram that represents 0.216.
c. Draw a diagram that represents 0.304.

Answers

Answer:

please where is the diagram

13. The coefficient in 8p + 897 is?
A. 8
B. p
C. =
D. 897​

Answers

Answer:

the correct answer is A. 8

8 is the answer , it’s the number placed with a variable before the next number or after the sign

help plsss-















it’s not letting me post omh :/

Answers

Answer:

20 fl ounce = 1 pt and 4 fl oz

Step-by-step explanation:

We want to convert fluid ounce to pint and fluid ounce

Mathematically;

Mathematically, 1 pint = 16 fluid ounce

Now we can write 20 fluid ounce as;

16 fl ounce + 4 fl ounce

Since 16 fl ounce is a pint, we have it that;

20 fluid ounce is 1 pt 4 fl oz

Kate has a coin collection. She keeps 7 of the coins in a box, which is only 5% of her entire collection. What is the total number of coins in Kate's collection?

A- 12
B- 14
C- 120
D- 140

Answers

Answer:

672

Step-by-step explanation:

7×95=665

665+7=672

the answer is 628292992929293747474849393939

Need help ASAP PLEASE !!!

Answers

Answer:

B.(-6,-1)

Step-by-step explanation:

CAN SOMEONE HELP ME PLEASE

Answers

The solution is acute angles

Answer:

x = 4, y = -3

Step-by-step explanation:

Find the slope intercept form first (y = mx + b):

the one going down is y = -1/2x - 1 (slope is negative, down 1 over 2, and the y-intercept is at (0, -1) )

the one going up is y = 1/4x - 4 (slope is up 1 over 4, and the y-intercept is at (0, -4)

Convert them into standard form (Ax + By = C):

1st equation: multiply the entirety of both sides by 2 to get rid of the fraction:

2y = -1x -`2

add 1x to both sides: 1x + 2y = -2

2nd equation: multiply the entirety of both sides by 4 to get rid of the fraction:

4y = 1x - 16

subtract 1x from both sides: -1x + 4y = -16

Isolate a variable:

-x + 4y = -16

-x = -4y - 16

x = 4y + 16

Plug that into other equation:

1(4y + 16) + 2y = -2

6y + 16 = -2

6y = -18

y = -3

Substitute y into the isolated equation:

x = 4(-3) + 16

x = -12 + 16

x = 4

It costs $3.95 to print a 12 in. by 16 in. color page. A friend needs to print a poster that is twice as long and twice as wide. At this rate, how much would he expect
to pay for the poster?

Answers

Answer:

$7.90

Step-by-step explanation:

Its is double both so u double $3.95

Price is determined by total area. The area of the original page is 192. If you calculate the area of the expanded posted, it would be 24*32. Which is 768. Find the scale factor of the areas, 768/192 is 4. 4*3.95 = 15.8. The price would be 15.80$.

What value of z makes this equation true?
Z+32=73+25
A.
66
B.
67
C.
80
D.
79

Answers

Answer:

a

Step-by-step explanation:

73+25=98

66+32=98

25 POINTS !!
4
Select the correct answer.
Consider this equalion
sin()
4729
29
If 0 is an angle in quadrant IV, what is the value of cos();
OA.
OB.
4729
29
V377
29
4729
29
377
29
O c.
OD.

Answers

The answer to this problem is in fact B

Answer:

B

Step-by-step explanation:

13. Connie wants to paint one wall in her living room. Along the wall, she
counted 60 pieces of hardwood that are each 6 cm wide. The wall is 8 feet
tall. Estimate the area of the wall she plans to paint. Round to the nearest
square foot. (1 foot approximately 30 cm)

Answers

Answer:  Approximately 96 square feet

======================================================

Work Shown:

1 ft = 30 cm

1 ft = (5*6) cm

1 ft = 5*(6 cm)

1 ft = 5*(1 board width)

1 ft = 5 board widths

12*(1 ft) = 12*(5 board widths)

12 ft = 60 board widths

12 ft = 1 full wall length

The wall is 12 feet horizontally across and 8 feet tall, so its estimated area is 12*8 = 96 square feet approximately. This is approximate because of the fact we used the approximation of 1 ft = 30 cm.

Beth is making fruit saladShe adds 5 grapes for every strawberriesshe uses 12 strawberries, how many grapes will use? Please help me!!

Answers

Answer:

She will use 60.

Step-by-step explanation:

12 x 5 = 60

Hope this helps ⭐

Answer:

Hello! Answer: 60

Step-by-step explanation:

If she is using 5 grapes per strawberries then we would do 12 x 5 = 60 and 60 is our answer.

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