Select True or False for each statement.

Suppose that a standardized biology exam has a mean score of 80% correct, with a standard deviation of 3. The school administrat

NemiM [27]

Answer:

The 99% confidence interval is between 62.36%(lower bound) and 89.64%(upper bound).

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

A sample of 65 students from the freshmen class is used and a mean score of 76% correct is obtained.

This means that $n = 65, \pi = 0.76$

99% confidence level

So $\alpha = 0.005$ , z is the value of Z that has a pvalue of $1 - \frac{0.005}{2} = 0.995$ , so $Z = 2.575$ .

The lower limit of this interval is:

$\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.76 - 2.575\sqrt{\frac{0.76*0.24}{65}} = 0.6236$

The upper limit of this interval is:

$\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.76 + 2.575\sqrt{\frac{0.76*0.24}{65}} = 0.8964$

0.6236*100 = 62.36%

0.8964*100 = 89.64%

The 99% confidence interval is between 62.36%(lower bound) and 89.64%(upper bound).

6 0

2 years ago

Systems of equations, help please?

lord [1]

4x + 3y = 54 (1)
3x + 9y = 108 (2)

Multiply (1) by (-3)
-12x - 9y = -162
3x + 9y = 108
---------------------add
-9x = -54
x = 6

plug x = 6 into (1) to find y
4(6) + 3y = 54
24 + 3y = 54
3y = 30
y = 10

Answer
(6 , 10)

Hope it helps.

3 0

3 years ago

Use the graph of the function. Determine Over what interval(s) the function is positive or negative.

san4es73 [151]

Answer:

I can't see the numbers well, but the graph is decreasing from (-inf, minimum) and increasing from (minimum, inf). The minimum is the vertex. Hope this helps!

Step-by-step explanation:

4 0

3 years ago

Which equation represents the line that passes through the points (-5,2) and (9,0)

V125BC [204]

Step-by-step explanation:

Given points 

( -5 , 2) and (9 , 0)

First calculating slope(m)

= ( y2 - y1) / ( x2 - x1) 

= ( 0-2) / ( 9+5)

= -2 / 14

= -1/7

Now The equation of line is given by 

y - y1 = m ( x - x1) 

y -2 = -1/7 (x + 5)

7( y - 2) = -1(x + 5)

7y - 14 = -x -5

x + 7y -14 +5 = 0

x + 7y - 9 = 0 

Which is the required equation 

7 0

3 years ago

Write (x+7)(x−2) as a sum

Dennis_Churaev [7]

Answer:

x^2+5x-14

Step-by-step explanation:

you multiply both equations so that you get:

x^2-2x+7x-14

and then you simplify it to:

x^2+5x-14

If you found this helpful please give it a thanks

I would also appreciate it if you give me a brainliest

8 0

2 years ago