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3 years ago

The focus of a parabola is located at (4,0), and the directrix is located at x = –4.

1 answer:

4 0

The distance between the focus and directrix is, in this case, 8. Since the directrix is at x= something, the parabola opens sideways, and since the directrix is on the left, to the right. In which case, y^2=p(x), where p is 4 times distance of half of distance between directrix and focus. So, the answer is D. y^2=16x. The 4th answer.

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Determine the margin of error for a 90% confidence interval to estimate the population mean when s = 40 for the sample sizes bel

Ann [662]

Answer:

a) The margin of error for a 90% confidence interval when n = 14 is 18.93.

b) The margin of error for a 90% confidence interval when n=28 is 12.88.

c) The margin of error for a 90% confidence interval when n = 45 is 10.02.

Step-by-step explanation:

The t-distribution is used to solve this question:

a) n = 14

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 = 14 - 1 = 13

90% confidence interval

Now, we have to find a value of T, which is found looking at the t table, with 13 degrees of freedom(y-axis) and a confidence level of $1 - \frac{1 - 0.9}{2} = 0.95$ . So we have T = 1.7709

The margin of error is:

$M = T\frac{s}{\sqrt{n}} = 1.7709\frac{40}{\sqrt{14}} = 18.93$

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

The margin of error for a 90% confidence interval when n = 14 is 18.93.

b) n = 28

27 df, T = 1.7033

$M = T\frac{s}{\sqrt{n}} = 1.7033\frac{40}{\sqrt{28}} = 12.88$

The margin of error for a 90% confidence interval when n=28 is 12.88.

c) The margin of error for a 90% confidence interval when n = 45 is

44 df, T = 1.6802

$M = T\frac{s}{\sqrt{n}} = 1.6802\frac{40}{\sqrt{45}} = 10.02$

The margin of error for a 90% confidence interval when n = 45 is 10.02.

3 0

2 years ago

1. 1/6 as a decimal and percent

butalik [34]

1. .1667 or 16%

2. X >_ 2. (Greater than or equal to)

3. X<-1

4. This one isn't an equation, but simplifies to 2x

4 0

3 years ago

The last part is function but need help asap

quester [9]

It would be the top one

4 0

3 years ago

Population: In a city of 40,000 people, there are 15,000 people under 25 years of age. What percent of the

egoroff_w [7]

Answer:

26 percent would be your answer.

6 0

3 years ago

horrorfan [7]

Step-by-step explanation:

charging the phone for 1 minute ,it has 2%

i.e,1----->2

After 2 minutes from that time ,i.e total 3 minutes

it has 6% charge

i.e,3--------->6

from the both the above cases ,1 minute provide 2%=6/3

Hence,

for getting 50%charge=50/2

=25 min

and,for 90 %charge=90\2

=45 min

8 0

2 years ago