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Sav [38]
3 years ago
7

Someone please help me?!?!

Mathematics
1 answer:
statuscvo [17]3 years ago
7 0
Holy guacamole....oml
You might be interested in
An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to make an est
malfutka [58]

Answer:

99% confidence interval for the true mean number of words a third grader can read per minute is [35.5 , 35.9].

Step-by-step explanation:

We are given that a sample of 1584 third graders, the mean words per minute read was 35.7. Assume a population standard deviation of 3.3.

Firstly, the pivotal quantity for 99% confidence interval for the population mean is given by;

                           P.Q. = \frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }  ~ N(0,1)

where, \bar X = sample mean words per minute read = 35.7

            \sigma = population standard deviation = 3.3

            n = sample of third graders = 1584

            \mu = population mean number of words

<em>Here for constructing 99% confidence interval we have used One-sample z test statistics as we know about the population standard deviation.</em>

<em />

So, 99% confidence interval for the population mean, \mu is ;

P(-2.58 < N(0,1) < 2.58) = 0.99  {As the critical value of z at 0.5% level

                                                  of significance are -2.58 & 2.58}  

P(-2.58 < \frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } } < 2.58) = 0.99

P( -2.58 \times {\frac{\sigma}{\sqrt{n} } } < {\bar X-\mu} < 2.58 \times {\frac{\sigma}{\sqrt{n} } } ) = 0.99

P( \bar X-2.58 \times {\frac{\sigma}{\sqrt{n} } } < \mu < \bar X+2.58 \times {\frac{\sigma}{\sqrt{n} } } ) = 0.99

<u>99% confidence interval for</u> \mu = [ \bar X-2.58 \times {\frac{\sigma}{\sqrt{n} } } , \bar X+2.58 \times {\frac{\sigma}{\sqrt{n} } } ]

                                                 = [ 35.7-2.58 \times {\frac{3.3}{\sqrt{1584} } } , 35.7+2.58 \times {\frac{3.3}{\sqrt{1584} } } ]

                                                 = [35.5 , 35.9]

Therefore, 99% confidence interval for the true mean number of words a third grader can read per minute is [35.5 , 35.9].

6 0
3 years ago
A cubic foot contains roughly 7 1/2 gallons. How many cubic feet are there in a tank containing 34 1/2 gallons
svlad2 [7]

Answer:

4.6 cubic feet

Step-by-step explanation:

take 34 1/2 gallons and divide it by 7 1/2 gallons

34.5 divided by 7.5 = 4.6

6 0
3 years ago
Factor completely 3x 2 + 2xy - y 2
sergij07 [2.7K]

Answer:

Final answer is (3x-y)(x+y).

Step-by-step explanation:

Given expression is 3x^2+2xy-y^2.

Now we need to factor the given expression 3x^2+2xy-y^2 completely. Let's use factor by grouping method.

3x^2+2xy-y^2

=3x^2+3xy-xy-y^2

=3x(x+y)-y(x+y)

=(3x-y)(x+y)

Hence final answer is (3x-y)(x+y).

5 0
3 years ago
Read 2 more answers
Evaluate the expression 1/2x - 2/3y when x = 4 and y = -3
ollegr [7]

Answer:

-1

Step-by-step explanation:

Equation: 1/2x-2/3y

Swap out the x and y with the numbers.

1/2 x 4/1 -2/3 x -3

Solve.

2-3

-1

3 0
3 years ago
Read 2 more answers
According to a "how to stop bullying" Web site, 15% of students report experiencing bullying one to three times within the most
AlekseyPX

Answer:

His 95% confidence interval is (0.065, 0.155).

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}.

For this problem, we have that:

n = 186, \pi = 0.11

95% confidence level

So \alpha = 0.05, z is the value of Z that has a pvalue of 1 - \frac{0.05}{2} = 0.975, so Z = 1.96.

The lower limit of this interval is:

\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.11 - 1.96\sqrt{\frac{0.11*0.89}{186}} = 0.065

The upper limit of this interval is:

\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.11 + 1.96\sqrt{\frac{0.11*0.89}{186}} = 0.155

His 95% confidence interval is (0.065, 0.155).

4 0
3 years ago
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