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Ksivusya [100]
3 years ago
7

4.8 Twitter users and news, Part I: A poll conducted in 2013 found that 55% of U.S. adult Twitter users get at least some news o

n Twitter (Pew, 2013). The standard error for this estimate was 2.6%, and a normal distribution may be used to model the sample proportion. Construct a 99% confidence interval for the fraction of U.S. adult Twitter users who get some news on Twitter, and interpret the confidence interval in context. (please round all percentages to 2 decimal places)
Mathematics
1 answer:
TiliK225 [7]3 years ago
7 0

Answer: Required 99% confidence interval  : (48.30%, 61.7%)

Step-by-step explanation:

Confidence interval for PROPORTION:  p\pm z^* \times S.E., where p = sample proportion , z* = two-tailed critical z-value  and S.E. = standard error.

As per given: p=55%

Critical z-value for 99% confidence = 2.576

S.E. = 2.6%

Then, required confidence interval :

55\% \pm (2.576)\times 2.6\%\\\\\approx55\% \pm6.70\%\\\\=(55\%-6.70\%,\ 55\%+6.70\%)\\\\=(48.30\%,\ 61.7\%)

Required 99% confidence interval  : (48.30%, 61.7%)

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Finger [1]

Answer:c

Step-by-step explanation:

I’m not sure lemme know if I’m wrong

5 0
3 years ago
Since opening night, attendance at Play A has increased steadily, while attendance at Play B first rose and then fell. Equations
Y_Kistochka [10]

Answer:

On 5th day and 13th day Attendance was equal for both plays and it was

231 for each .

Step-by-step explanation:

In order to find same attendance ,we need  plug both equation equal

         -x^2+26x+126 = 8x+191

        -x^2+26x-8x+126-191 = 0

        -x^2 +18x-65 =0

      multiplying both sides by -1 ,we get

      x^2 -18x+ 65 =0

        (x-5) (x-13) =0

         x =5 and x =13

On 5th day and 13th  day attendance was same.

And attendance can be obtained by plugging x =5 in either of equation

 y = 8(5)+191

   = 40 +191

  = 231

 

8 0
3 years ago
Which one of the colors do I choose to pick
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Answer:

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5 0
3 years ago
Read 2 more answers
❗️Please help BIG POINTS❗️
Inessa [10]
Dude, what kind of question is this??? Here's my best shot.
If they start at the 32-mile mark, then the we can use 32 as the intercept. 50 can be the change in position over time, so 
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5 0
3 years ago
Kesha threw her baton up in the air from the marching band platform during practice. The equation h(t) = −16t² + 54t + 40 gives
lapo4ka [179]

Answer:

a) 40 feet

b) 54 ft/min

c) 4 mins

Step-by-step explanation:

Solution:-

- Kesha models the height ( h ) of the baton from the ground level but thrown from a platform of height hi.

- The function h ( t ) is modeled to follow a quadratic - parabolic path mathematically expressed as:

                           h ( t ) = −16t² + 54t + 40

Which gives the height of the baton from ground at time t mins.

- The initial point is of the height of the platform which is at a height of ( hi ) from the ground level.

- So the initial condition is expressed by time = 0 mins, the height of the baton h ( t ) would be:

                         h ( 0 ) = hi = -16*(0)^2 + 54*0 + 40

                         h ( 0 ) = hi = 0 + 0 + 40 = 40 feet

Answer: The height of the platform hi is 40 feet.

- The speed ( v ) during the parabolic path of the baton also varies with time t.

- The function of speed ( v ) with respect to time ( t ) can be determined by taking the derivative of displacement of baton from ground with respect to time t mins.

                        v ( t ) = dh / dt

                        v ( t )= d ( −16t² + 54t + 40 ) / dt

                        v ( t )= -2*(16)*t + 54

                        v ( t )= -32t + 54

- The velocity with which Kesha threw the baton is represented by tim t = 0 mins.

Hence,

                        v ( 0 ) = vi = -32*( 0 ) + 54

                        v ( 0 ) = vi = 54 ft / min

Answer: Kesha threw te baton with an initial speed of vo = 54 ft/min

- The baton reaches is maximum height h_max and comes down when all the kinetic energy is converted to potential energy. The baton starts to come down and cross the platform height hi = 40 feet and hits the ground.

- The height of the ball at ground is zero. Hence,

                     h ( t ) = 0

                     0 = −16t² + 54t + 40

                     0 = -8t^2 + 27t + 20

- Use the quadratic formula to solve the quadratic equation:

                     

                    t = \frac{27+/-\sqrt{27^2 - 4*8*(-20)} }{2*8}\\\\t = \frac{27+/-\sqrt{1369} }{16}\\\\t = \frac{27+/-37 }{16}\\\\t =  \frac{27 + 37}{16} \\\\t = 4

Answer: The time taken for the baton to hit the ground is t = 4 mins

3 0
3 years ago
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