A random sample of 21 desktop PCs is selected. The mean life span is 6.8 years with a standard deviation of 2.4 years. Construct a 95% confidence interval for the mean life span of all desktop PCs. Assume that the life spans of all desktop PCs are approximately normally distributed (a) (5.85, 7.75) (b) (1.68, 3.12) (c) (5.60, 8.00) (d) (5.71, 7.89) (e) (5.77, 7.83)

Answers

Answer 1

Answer:

(d) (5.71, 7.89)

Step-by-step explanation:

We have the standard deviation for the sample, which means that the t-distribution is used to solve this question.

The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So

df = 21 - 1 = 20

95% confidence interval

Now, we have to find a value of T, which is found looking at the t table, with 20 degrees of freedom(y-axis) and a confidence level of [tex]1 - \frac{1 - 0.95}{2} = 0.975[/tex]. So we have T = 2.086

The margin of error is:

[tex]M = T\frac{s}{\sqrt{n}} = 2.086\frac{2.4}{\sqrt{21}} = 1.09[/tex]

In which s is the standard deviation of the sample and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 6.8 - 1.09 = 5.71 years

The upper end of the interval is the sample mean added to M. So it is 6.8 + 1.09 = 7.89 years

So the confidence interval is (5.71, 7.89), and the correct answer is given by option b.


Related Questions

Select the correct answer.
Given: ABC with DE||AC
Prove: AD/DB = CE/EB​

Answers

Answer:

AB/DB = CB/EB

Step-by-step explanation:

This is the answer on Pluto. I got lucky when I guessed

The solution is given below.

What is alternate angles?

The alternate exterior angle theorem states that if two lines are parallel and are intersected by a transversal, then the alternate exterior angles are considered as congruent angles or angles of equal measure.

Here  given:  

AB II DE, AC = CE

Now, in ΔABC and ΔEDC

As,  AB II DE (given)

⇒∠BAC = ∠CED   (Alternative pairs of angles)

and  ∠ABC = ∠CDE  (Alternative pairs of angles)

and AC = CE (given)

So, by the congruent  property of AAS

(ANGLE ANGLE SIDE) which states that two triangle are congruent if two angles and one side of one triangle is equal to the two angles and one side of the other triangle.

                               ΔABC ≅  ΔEDC

to learn more on alternate angle click:

brainly.com/question/7197938

#SPJ7

complete question:

Given: AB II DE, AC = CE

Prove: A ABC = A EDC

don’t understand this help please

Answers

Step-by-step explanation:

Since he sold $70,834 worth of cars, he earned an extra 5% commission on the sale. That means he got

0.05×($70,834) = $3,541.70

Therefore, his salary for the month m is

m = $2250 + 0.05s = $2,250 + $3,541.70 = $5,791.70

Andy's average driving speed for a 4 hour trip was 48 miles per hour. During the first 3 hours he drove 50 miles per hour. What was his average speed for the last hour on his trip.

PLEASE HELP AND SHOW WORK YOU WILL GET BRAINLEST MARK

Answers

Answer:

Step-by-step explanation:

Distance = 48 * 4

Distance = 192

~~~~~~~~~~~~~~~

3*50 = 150

192 - 150 = 42

42 MPH for the last hour

The perimeter of a rectangle is 12cm the area is 5cm square what is the length of the sides

Answers

Answer:

???

Step-by-step explanation:

L=5 and w=1
Hope this helps

Choose the equation of the line that is parallel to the y-axis.
x = -2
x + y = 0
x = y
y = 2

Answers

Answer:

x=-2

Step-by-step explanation:

If x always = -2, it is a straight vertical line which means it is parallel to the y axis

it's x=-2 because anything just on the x axis without a y is vertical which is parallel to the y axis

find the equation of common tangent of x²+y²=4ax and y²=4ax.​

Answers

Step-by-step explanation:

x² +4ax+y² =0

x² +4ax+4a² +y² =4a²

(x+2a) ² +y² =4a² ......(i)

y² =4ax.........(ii)

By tracing the circle and the parabola we can clearly see that they touch each other along the y axis

So the equation of common tangent is x=0.

Find tan 0, where is the angle shown. Give an exact value, not a decimal approximation. (PLZ HELP DUE SOON I GIVE BRAINLIST :D)​

Answers

Answer:

[tex]\frac{24}{7}[/tex]

Step-by-step explanation:

Tanθ=Opposite/Adjacent

we have the adjacent side but need the oppsoite

We will use a²+b²=c²

25²=7²+b²

576=b²

b=24

Therefore the answer is

[tex]\frac{24}{7}[/tex]

Jenny made 200 bracelets. She sold 64% of the bracelets at a craft fair.
a. How many bracelets did she sell?
b. How many bracelets were not sold?

Answers

Step-by-step explanation:

shslsfauahcaiscwrwpagw6wpwfwyw

Answer:

Jenny sold 128 braclets. 72 bracelets weren't sold.

Step-by-step explanation:

IMPORTANT FORMULA: TO CONVERT A NUMBER TO A PERCENT, YOU HAVE TO MULTIPLY BY 100. TO CONVERT A PERCENT TO A NUMBER, YOU HAVE TO DIVIDE BY 100.

a) How many bracelets did she sell?

Using the formula that is shown above, I can conclude that 64%=64/100=32/50=16/25

Jenny sold 64% of the 200 bracelets.

In mathematics, the word "of" means multiplication.

64% of 200 = 16/25 * 200 = 128

Jenny sold 128 braclets.

to answer part 2, 200 bracelets - 128 bracelets = 72 bracelets.

72 bracelets weren't sold.

Yes i give brainliest​

Answers

D

It can give some balls more chance to be picked, making it unfair

(x-7)(x^2+3x-3) multiply the polynomials

Answers

Step-by-step explanation:

= (x - 7)(x² + 3x - 3)

= x³ - 7x² + 3x² - 21x - 3x + 21

= x³ - 4x² - 24x + 21

Point B has coordinates (4,2). The x-coordinate of point A is - 1. The distance between point A and
point B is 13 units. What are the possible coordinates of point A?

Answers

Answer:

A (-1,-10) ; A (-1,14)

Step-by-step explanation:

[tex]\sqrt{(-1-4)^2 + (y-2)^2} = 13 \\ 25 + y^2 + 4 -4y = 169[/tex]

y^2 -4y - 140 = 0

Δ/4 = 4 + 140 = 144

y1 = 2 + 12 = 14

y2 = 2 -12= -10

The list price on slacks is $22, and the list price on jumpers is $37. If Petit’s Clothing Store orders 30 pairs of slacks and 40 jumpers at a discount rate of 11%, what is the trade discount on the purchase?

Answers

Step-by-step explanation:

Calculate the value of decimal equivalents of complements, net decimal equivalent and net price with the help of given data:

List price= $200

Trade discount series= 20/10

Calculate the decimal equivalents of complements using given formula:

Complements of successive discount = 

= 80% / 90%

Hence, decimal equivalent of complements are 80% / 90%.

Answer:

Trade discount = $235.40

Step-by-step explanation:

List price :

Slacks = 22

Jumpers = 37

Total amount before discount = (30 x 22) + ( 40 x 37)

                                              = 660  +  1480

                                              = 2140

Discount rate = 11%

So,

  [tex]Discount \ price = 11 \% \ of \ 2140\\\\Discount \ price = \frac{11}{100} \times 2140 = 235.40[/tex]

có bao nhiêu hình tứ giác

Answers

Answer:

si si amigo adila

Step-by-step explanation:

How much will you have if : S900 invested at 6% compounded semiannually
for 5 years.

Answers

Answer:

Step-by-step explanation:

A = P(1+r/n)^nt

A = 900(1 + .06/2)^(5*2)

A = 900(1.03)^10

A=1209.52

7) -4 = 2(b + 5)
please help!

Answers

Answer:

b = -7

Step-by-step explanation:

Let's solve your equation step-by-step.

−4 = 2(b + 5)

Step 1: Simplify both sides of the equation.

−4 = 2(b + 5)

−4 = (2)(b) + (2)(5)(Distribute)

−4 = 2b + 10

Step 2: Flip the equation.

2b + 10 = −4

Step 3: Subtract 10 from both sides.

2b + 10 − 10 = −4 − 10

2b = −14

Step 4: Divide both sides by 2.

[tex]\frac{2b}{2} = \frac{-14}{2}[/tex]

b = -7

Hope this helps, please mark brainliest if possible. Have a great day! :)

Use substitution to solve the system of equations and choose the solution from the list below.
Look at the image

Answers

Answer:

Option : ( 2 , 6 )

x = 2, y = 6

Step-by-step explanation:

[tex]y = 4x - 2[/tex]      ---------------- ( 1 )

[tex]y = -2x + 10[/tex]   -------------- ( 2 )

Substitution Method

Substitute ( 1 ) in ( 2 ) :

                           [tex]4x - 2 = -2x + 10\\\\4x + 2x = 10 + 2\\\\6x = 12\\\\x = 2[/tex]

Now substitute x in ( 2 ):

                           [tex]y = -2x + 10\\\\y = -2 ( 2 ) + 10\\\\y = - 4 + 10 \\\\y = 6[/tex]

x-value of 0
f(x) = |x|
f(x) = |x| + 3
f(x) = |x + 3|
f(x) = |x| − 6
f(x) = |x + 3| – 6

Answers

9514 1404 393

Answer:

  0, 3, 3, -6, -3

Step-by-step explanation:

Maybe you want to find f(0) in each case. Put 0 where x is, and do the arithmetic.

  f(0) = |0| = 0

  f(0) = |0| +3 = 3

  f(0) = |0 +3| = 3

  f(0) = |0| -6 = -6

  f(0) = |0 +3| -6 = -3

2x-4=20
Please fast with steps !

Answers

Answer:

x=12

hope it will helpful to you

HELP !!!! look at the picture

Answers

Answer:

Option C:

g(x) = -3^x

Step-by-step explanation:

Here we can see the graphs of f(x) and the graph of g(x).

By only looking at that, we can see that g(x) is a reflection across the x-axis of f(x).

Remember that for a general function f(x), the reflection across the x-axis is written as:

g(x) = -f(x).

Then, if f(x) = 3^x

and g(x) = -f(x)

replacing f(x) we get:

g(x) = -(3^x) = -3^x

The correct option is C.

What is the greatest solution of x in the equation x2 + 8x - 30 = 18?
Enter your answer in the box.

Answers

9514 1404 393

Answer:

  x = 4

Step-by-step explanation:

Subtracting 18,  we have the equation ...

  x^2 +8x -48 = 0

  (x +12)(x -4) = 0 . . . . . factored form

The values of x that make these factors zero are the solutions:

  x = -12, x = 4

The greatest solution is x=4.

Answer:

Greatest solution of x = 4

Step-by-step explanation:

x² + 8x - 30 = 18

subtract 18 from both sides

x² + 8 x - 30 - 18 = 18 - 18

x ² + 8 x - 48 = 0

split 8x in middle form

x² + ( 12 x - 4 x ) - 48 = 0

factor out x from the first pair

x ( x + 12 ) - ( 4 x- 48 ) = 0

factor out 4 from the second pair

x ( x + 12) - 4 ( x + 12 ) = 0

x + 12 is common factor

x ( x + 12) - 4 ( x + 12 ) = 0

Group common factor

(x - 4) ( x + 12 ) = 0

When the product of factors equal 0, at least one factor is 0.

x - 4 = 0

x = 4

similarly,

x + 12 = 0

x = - 12

Greatest solution of x = 4

ASSESSMENT:
Act as the person in the problem Do the activity. Record your
findings then answer

1. A farmer placed 250 mangoes in a crate, these are 150 ripe and 100 unripe
mangoes, his wife randomly selected 80 mangoes, she got 50 ripe mangoes
and 20 unripe mangoes, find the experimental probability of the mangoes she
selected.

2. A table tennis player has 40 orange table tennis balls, 30 white and 20 yellow
table tennis balls. After selecting 18 balls, he found out that he got 6 white
table tennis balls. Find out the experimental probability of getting white table
tennis table tennis balls.

please answer this ​

Answers

Answer:

in 1st his wife selected 80 mangoes 50 ripe and 20 unripe how it can be

Step-by-step explanation:

50+20=70 not 80

please share the correct question than I may help you

Intersection and conditional probability problem. Can anyone help solve this problem?

Answers

Part (a)

Refer to figure 1 in the attached image below. The a,b,c,d,e are placeholders for numbers we'll fill in later (that turns into the table for figure 2). Hopefully you agree about the placement of the numbers. If there's any confusion, then please let me know.

Along the bottom row, we can see that 39+e = 65 which solves to e = 26 after you subtract 39 from both sides. This tells us that there are 26 non-physics majors (ie their major is anything but physics).

Then along the "non-physics" column, notice how b+6 = e, which is the same as b+6 = 26 after replacing 'e' with 26. Solving that equation leads to b = 20. So we have 20 people who are seniors and non-physics majors.

Now move to the top row. We can see that a+b = 30, which is the same as a+20 = 30 because we plug in b = 20. That solves to a = 10. So we have 10 seniors who are physics majors.

----------------

Now along the first column, we have a+c = 39, aka 10+c = 39, which solves to c = 29. There are 29 non-seniors who are physics majors.

The last variable to find is variable d.

Along the second row, we can say,

c+6 = d

29+6 = d

d = 35

Or we could say that 30+d = 65 along the last column which also solves to d = 35. This tells us we have 35 non-seniors in the class.

----------------

To summarize so far, we have

a = 10, b = 20, c = 29, d = 35, e = 26

These values will replace the letters as shown in figure 2.

Figure 2 will be used to answer both parts (a) and (b).

----------------

After that (more than) slight detour of filling in the table, we can finally tackle the question at hand. We're asked to find the probability of selecting someone who is a senior and a physics major. We have a = 10 people who fit the description out of 65 total

Divide the two values and reduce the fraction as much as possible

10/65 = (2*5)/(13*5) = 2/13

Answer:   2/13

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

Part (b)

There's a lot going on with part (a). Luckily there aren't many steps here because pretty much all the work has been done already. We'll refer to figure 2 below.

We're told "given the student is a physics major", which means we focus solely on the "physics major" column only. We ignore everyone else because we know 100% that whoever we selected majored in physics.

We have a = 10 seniors who are also physics majors out of 39 physics majors total.

That constructs the fraction 10/39

Answer: 10/39

The circumference of the base of the cone is 8.5 inches. What is the volume of the cone in term of pi? Round to the nearest hundredth

Answers

Answer:  V = 270.94/pi

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

Work Shown:

C = 2*pi*r  ......... circumference of the circular base

r = C/(2pi)

r = (8.5)/(2pi)

r = 4.25/pi

-------------

V = pi*r^2*h ...... volume of the cone

V = pi*(4.25/pi)^2*15

V = pi*(18.0625/pi^2)*15

V = (18.0625*15)/pi

V = 270.9375/pi ..... exact volume in terms of pi

If we round that decimal number up top to the nearest hundredth, then we end up with V = 270.94/pi

What are the center and radius of the circle defined by the equation x^2 + y^2 -6x + 8y + 21=0

Answers

Answer:

Step-by-step explanation:

(x²-6x)+(y²+8y)=-21

(x²-6x+9)+(y²+8y+16)=-21+9+16

(x-3)²+(y+4)²=4

center=(3,-4),radius=√4=2

A right cone has a surface area of 440 square inches and a radius of 7 inches. Find its slant height.

Answers

Answer:

13 inches

Step-by-step explanation:

Surface area of a right cone = pi*r(r+L)

i,e, 440 = 22/7*7(7+L)

440 = 22(7+L)

440 = 154 + 22L

440 - 154 = 22L

286 = 22L

286/22 = L

13 = L

Therefore the slant height is 13inches

Hope u understand

Thank You

If f(x) is a linear function, f(−2)=4, and f(1)=−1, find an equation for f(x)

Answers

Answer:

[tex]y = -\frac{5}{3}x+\frac{2}{3}[/tex]

Step-by-step explanation:

Given

[tex]f(-2) = 4[/tex]

[tex]f(1) = -1[/tex]

Required

The equation of the function

The given parameters means that:

[tex](x_1,y_1) = (-2,4)[/tex]

[tex](x_2,y_2) = (1,-1)[/tex]

Calculate the slope (m)

[tex]m = \frac{y_2 -y_1}{x_2 -x_1}[/tex]

[tex]m = \frac{-1-4}{1--2}[/tex]

[tex]m = \frac{-5}{3}[/tex]

The equation is then calculated using:

[tex]y = m(x - x_1) + y_1[/tex]

This gives:

[tex]y =\frac{-5}{3}(x--2)+4[/tex]

[tex]y =\frac{-5}{3}(x+2)+4[/tex]

Open bracket

[tex]y = -\frac{5}{3}x-\frac{10}{3}+4[/tex]

Take LCM

[tex]y = -\frac{5}{3}x+\frac{-10+12}{3}[/tex]

[tex]y = -\frac{5}{3}x+\frac{2}{3}[/tex]

If a total of 360 students were involved in the evening's activities, how many students attend the school?

Answers

390

360 = 12x/13
30 = x/13
390 = x

The population of a rabbit colony triples each month.

The population started with 5 rabbits. How many

rabbits are there after 6 months?

Answers

Answer:

3645 rabbits after 6 months.

Step-by-step explanation:

The population of a rabbit colony triples each month.

This means that the population of the colony after t months is given by:

[tex]P(t) = P(0)(3)^t[/tex]

In which P(0) is the initial population.

The population started with 5 rabbits.

This means that [tex]P(0) = 5[/tex]

So

[tex]P(t) = 5(3)^t[/tex]

How many rabbits are there after 6 months?

This is P(6). So

[tex]P(6) = 5(3)^6 = 3645[/tex]

3645 rabbits after 6 months.

Selena Gomez is running the Gary Mintz Marathon. After 6 miles, Selena Gomez's clock reads 48 minutes. If Selena Gomez maintains her current pace, what will her clock read at 20 miles? You can use the table below to calculate her times.
A : 56
B: 160
C: 140
D: 96

Answers

Answer:

The answer would be C: 140.

Divide the following two complex numbers.
3+2i
5-3i

Answers

Step-by-step explanation & answer:

Conjugate = 5+3i

Multiply fraction by conjugate:

(15+9i+10i+6i^2) / (25-9i^2)

Simplify:

(15+19i+6i^2) / (25-9i^2)

i^2 is -1:

(15+19i-6) / (25+9)

So:

9+19i / 34

Into a +bi form:

9/34 + 19i/34

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