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3 years ago

Pls help me and i will know if it is wrong

Mathematics

1 answer:

DENIUS [597]3 years ago

8 0

9514 1404 393

Answer:

90 miles

Step-by-step explanation:

Let d represent the distance to Grandma's house.

The speed going was ...

speed = distance/time

speed = d/2

The speed coming home was ...

speed = d/2.25

The difference of these speeds is 5 miles per hour:

d/2 -d/2.25 = 5

2.25d -2d = 5(4.50) . . . . . multiply by 4.50

0.25d = 22.5 . . . . . . . . . . .simplify

d = 90 . . . . . . . . . . . . . . . . multiply by 4

Grandma's house is 90 miles away.

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A researcher wants to estimate the percentage of all adults that have used the Internet to seek pre-purchase information in the

Lubov Fominskaja [6]

Answer:

The required sample size for the new study is 801.

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 $1 - \frac{\alpha}{2}$ .

The margin of error is:

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

25% of all adults had used the Internet for such a purpose

This means that $\pi = 0.25$

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 $Z = 1.96$ .

What is the required sample size for the new study?

This is n for which M = 0.03. So

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

$0.03 = 1.96\sqrt{\frac{0.25*0.75)}{n}}$

$0.03\sqrt{n} = 1.96\sqrt{0.25*0.75}$

$\sqrt{n} = \frac{1.96\sqrt{0.25*0.75}}{0.03}$

$(\sqrt{n})^2 = (\frac{1.96\sqrt{0.25*0.75}}{0.03})^2$

$n = 800.3$

Rounding up:

The required sample size for the new study is 801.

4 0

2 years ago

What is a point-slope equation of the line with slope -10 that goes through the point (1,4)

KatRina [158]

$\bf (\stackrel{x_1}{1}~,~\stackrel{y_1}{4})\qquad \qquad \qquad 
% slope = m
slope = m\implies -10
\\\\\\
% point-slope intercept
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8 0

2 years ago

Read 2 more answers

What’s 0.005 recurring as a fraction

PilotLPTM [1.2K]

Answer:

0.005 = 5/1000 = 1/200

Hope it helps

3 0

3 years ago

Huddson has practiced a 360-back flip for months. This week, he did it perfectly 24 out of 54 times. At this rate, how many time

iris [78.8K]

Let x = perfect flips out of nine
$\frac{24}{54} = \frac{x}{9}$
$54x = 216$
$x = 4$
4 flips

5 0

3 years ago

Help pls- <br><br> I dont know it T^T

docker41 [41]

Answer:

Ans: H and A

Step-by-step explanation:

By the identity:

1-(cos(x)) $cos^{2}(x)+ sin^{2}(x)=1\\cos^{2}(x)=1- sin^{2}(x)\\\\cos(x)=\sqrt{1- sin^{2}(x)} \\sin(x)=\sqrt{1- cos^{2}(x)}\\\\\sqrt{1- cos^{2}(x)}/sinx=1\\\sqrt{1- sin^{2}(x)}/cosx=1\\\sqrt{1- cos^{2}(x)}/sinx+\sqrt{1- sin^{2}(x)}/cosx=2\\\\\\$

Ans: H

For second quesiton, the transformation of a graph is that:

f(x) + k means vertical translation up by k units

Two curve have the same maximum value, so the graph doesn't translate upwards or downwards, thus b=0

Ans: A

7 0

2 years ago