What do you call it when 50 people stand on a wooden dock

The U.S. Energy Information Administration (US EIA) reported that the average price for a gallon of regular gasoline is $2.94. T

Anit [1.1K]

Answer:

a) 25

b) 67

c) 97

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.95}{2} = 0.025$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.025 = 0.975$ , so $z = 1.96$

Now, find the margin of error M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample. In this problem, $\sigma = 0.25$

(a) The desired margin of error is $0.10.

This is n when M = 0.1. So

$M = z*\frac{\sigma}{\sqrt{n}}$

$0.1 = 1.96*\frac{0.25}{\sqrt{n}}$

$0.1\sqrt{n} = 1.96*0.25$

$\sqrt{n} = \frac{19.6*0.25}{0.1}$

$(\sqrt{n})^{2} = (\frac{19.6*0.25}{0.1})^{2}$

$n = 24.01$

Rounding up to the nearest whole number, 25.

(b) The desired margin of error is $0.06.

This is n when M = 0.06. So

$M = z*\frac{\sigma}{\sqrt{n}}$

$0.06 = 1.96*\frac{0.25}{\sqrt{n}}$

$0.06\sqrt{n} = 1.96*0.25$

$\sqrt{n} = \frac{19.6*0.25}{0.06}$

$(\sqrt{n})^{2} = (\frac{19.6*0.25}{0.06})^{2}$

$n = 66.7$

Rounding up, 67

(c) The desired margin of error is $0.05.

This is n when M = 0.05. So

$M = z*\frac{\sigma}{\sqrt{n}}$

$0.05 = 1.96*\frac{0.25}{\sqrt{n}}$

$0.05\sqrt{n} = 1.96*0.25$

$\sqrt{n} = \frac{19.6*0.25}{0.05}$

$(\sqrt{n})^{2} = (\frac{19.6*0.25}{0.05})^{2}$

$n = 96.04$

Rounding up, 97

8 0

2 years ago

Just need to check these answers

amid [387]

Great Job! they are all correct. :)

Good luck in your next tests.

3 0

2 years ago

Repeated student samples. Of all freshman at a large college, 16% made the dean’s list in the current year. As part of a class p

Dima020 [189]

Answer:

a) p-hat (sampling distribution of sample proportions)

b) Symmetric

c) σ=0.058

d) Standard error

e) If we increase the sample size from 40 to 90 students, the standard error becomes two thirds of the previous standard error (se=0.667).

Step-by-step explanation:

a) This distribution is called the <em>sampling distribution of sample proportions</em> <em>(p-hat)</em>.

b) The shape of this distribution is expected to somewhat normal, symmetrical and centered around 16%.

This happens because the expected sample proportion is 0.16. Some samples will have a proportion over 0.16 and others below, but the most of them will be around the population mean. In other words, the sample proportions is a non-biased estimator of the population proportion.

c) The variability of this distribution, represented by the standard error, is:

$\sigma=\sqrt{p(1-p)/n}=\sqrt{0.16*0.84/40}=0.058$

d) The formal name is Standard error.

e) If we divided the variability of the distribution with sample size n=90 to the variability of the distribution with sample size n=40, we have:

$\frac{\sigma_{90}}{\sigma_{40}}=\frac{\sqrt{p(1-p)/n_{90}} }{\sqrt{p(1-p)/n_{40}}}}= \sqrt{\frac{1/n_{90}}{1/n_{40}}}=\sqrt{\frac{1/90}{1/40}}=\sqrt{0.444}= 0.667$

If we increase the sample size from 40 to 90 students, the standard error becomes two thirds of the previous standard error (se=0.667).

0 0

2 years ago

Maddy is carrying a 555 liter jug of sports drink that weighs 7.5\text{ kg}7.5 kg7, point, 5, start text, space, k, g, end text.

Lelu [443]

Answer:

w/2 = 7.5/5

3kg

Step-by-step explanation:

Remaining question below:

Which proportion could Maddy use to model this situation?

a. w/2 = 7.5/5

b. w/7.5 = 5/2

Solve the proportion to determine the weight of a 2 liter jug.

_____kg

5 liters jug of sport drink weighs 7.5kg

2 liters jug of sport drink will weigh x kg

Find w

Ratio of weight to volume

7.5kg : 5liters=7.5/5

wkg : 2 liters=w/2

Equates the ratio

7.5 / 5 = w / 2

Cross product

7.5*2=5*w

15=5w

Divide both sides by 5

3=w

w=3kg

Therefore, weight of the 2liters jug of sport drink is 3kg

6 0

2 years ago

Read 2 more answers

A sports car and a minivan run out of gas and are pushed to the side of the road. Which is easier to push, and why?

nirvana33 [79]

Answer:

The sports car, because it has less mass and therefore less inertia

Step-by-step explanation:

When an object has less inertia it is easier to be put into and out of motion, and a sports car would obviously weigh less than a van.

5 0

2 years ago

Read 2 more answers